Also fix a shadowed error variable bug.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5573072

Fixes #2773.

R=rsc
CC=golang-dev
https://golang.org/cl/5571056

R=rsc
CC=golang-dev
https://golang.org/cl/5555072

It means serious user error that can lead to
hard to debug issues under load, log entry
will not harm.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5574075

Fixes #2781.

R=golang-dev, rsc
CC=golang-dev, mpimenov
https://golang.org/cl/5577053

Fixes test/reorder2.go for all cases tripped up with -lll in 5555072

R=rsc
CC=golang-dev
https://golang.org/cl/5569069

Fixes #2752.

R=golang-dev, mpimenov, r
CC=golang-dev
https://golang.org/cl/5571062

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5572064

If there's an error, sometimes you need to stop.
Part of issue 2787.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5570068

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5569067

Fixes #2784

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5574073

The idea is that we add files to the api/ directory which
are sets of promises for the future.  Each line in a file
is a stand-alone feature description.

When we do a release, we make sure we haven't broken or changed
any lines from the past (only added them).

We never change old files, only adding new ones. (go-1.1.txt,
etc)

R=dsymonds, adg, r, remyoudompheng, rsc
CC=golang-dev
https://golang.org/cl/5570051

Fixes #2699

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5557063

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5577051

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5573071

R=golang-dev, iant, adg
CC=golang-dev
https://golang.org/cl/5574072

R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/5575056

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/5574071

Separating Method from Func made the code only more complicated
without adding much to the useability/readability of the API.
Reverted to where it was, but leaving the new method-specific
fields Orig and Level.

Former clients (godoc) of doc.Method only used the Func fields;
and because Func was embedded, no changes are needed with respect
to the removal of Method.

Changed type of Func.Recv from ast.Expr to string. This was a
long-standing TODO. Also implemented Func.Orig field (another TODO).

No further go/doc API changes are expected for Go 1.

R=rsc, r, r
CC=golang-dev
https://golang.org/cl/5577043

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/5577050

This improves the handling of xml.Unmarshal in
the xmlapi fix by guessing some of the common
types used on it.

This also fixes a bug in the partial typechecker.
In an expression such as f(&a), it'd mark a as
having &T rather than *T.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5572058

Roughly 2x speedup for the internal bitLen function in arith.go.  Added TestWordBitLen test.

Performance differences against the new version of
bitLen generic:

x86-64 Macbook pro (current tip):

benchmark                old ns/op    new ns/op    delta
big.BenchmarkBitLen0             6            4  -37.40%
big.BenchmarkBitLen1             6            2  -51.79%
big.BenchmarkBitLen2             6            2  -65.04%
big.BenchmarkBitLen3             6            2  -66.10%
big.BenchmarkBitLen4             6            2  -60.96%
big.BenchmarkBitLen5             6            2  -55.80%
big.BenchmarkBitLen8             6            2  -56.19%
big.BenchmarkBitLen9             6            2  -64.73%
big.BenchmarkBitLen16            7            2  -68.84%
big.BenchmarkBitLen17            6            2  -67.11%
big.BenchmarkBitLen31            7            2  -61.57%

386 Intel Atom (current tip):
benchmark                old ns/op    new ns/op    delta
big.BenchmarkBitLen0            23           20  -13.04%
big.BenchmarkBitLen1            23           20  -14.77%
big.BenchmarkBitLen2            24           20  -19.28%
big.BenchmarkBitLen3            25           20  -21.57%
big.BenchmarkBitLen4            24           20  -16.94%
big.BenchmarkBitLen5            25           20  -20.78%
big.BenchmarkBitLen8            24           20  -19.28%
big.BenchmarkBitLen9            25           20  -20.47%
big.BenchmarkBitLen16           26           20  -23.37%
big.BenchmarkBitLen17           26           20  -25.09%
big.BenchmarkBitLen31           32           20  -35.51%

ARM v5 SheevaPlug, previous weekly patched with bitLen:
benchmark                old ns/op    new ns/op    delta
big.BenchmarkBitLen0            50           29  -41.73%
big.BenchmarkBitLen1            51           29  -42.75%
big.BenchmarkBitLen2            59           29  -50.08%
big.BenchmarkBitLen3            60           29  -50.75%
big.BenchmarkBitLen4            59           29  -50.08%
big.BenchmarkBitLen5            60           29  -50.75%
big.BenchmarkBitLen8            59           29  -50.08%
big.BenchmarkBitLen9            60           29  -50.75%
big.BenchmarkBitLen16           69           29  -57.35%
big.BenchmarkBitLen17           70           29  -57.89%
big.BenchmarkBitLen31           95           29  -69.07%

R=golang-dev, minux.ma, gri
CC=golang-dev
https://golang.org/cl/5574054

This patch intend to fix following issues.
http://code.google.com/p/go/issues/detail?id=2616

Fixes #2616.

R=golang-dev, bradfitz, nekotaroh
CC=golang-dev
https://golang.org/cl/5532057

Pulling function calls out to happen before the
expression being evaluated was causing illegal
reorderings even without inlining; with inlining
it got worse.  This CL adds a separate ordering pass
to move things with a fixed order out of expressions
and into the statement sequence, where they will
not be reordered by walk.

Replaces lvd's CL 5534079.

Fixes #2740.

R=lvd
CC=golang-dev
https://golang.org/cl/5569062

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5573069

R=golang-dev, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/5573060

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5569059

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5569065

R=rsc
CC=golang-dev
https://golang.org/cl/5570043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5574067

I said rm, but not hg rm.
I never was good at Simon says.

TBR=bradfitz
CC=golang-dev
https://golang.org/cl/5574066

The real fix for Issue 2616 is in
https://golang.org/cl/5532057, to be submitted
following this CL, without the test there which doesn't work
reliably. This one seems to.

R=rsc
CC=golang-dev
https://golang.org/cl/5569063

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5569064

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5576044

R=rsc, r
CC=golang-dev
https://golang.org/cl/5564055

Python and Mercurial are a matched pair.

R=adg
CC=golang-dev
https://golang.org/cl/5570065

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5564054

Added a cache to compensate for extra call overhead.
go test -bench=Print marginally faster (in the noise).

R=r
CC=golang-dev
https://golang.org/cl/5574061

No changes when applying gofmt to src, misc.

Fixes #2597.

R=r
CC=golang-dev
https://golang.org/cl/5564056

R=rsc
CC=golang-dev
https://golang.org/cl/5575055