This avoids a non-obvious panic when range is used on a
nil interface, and fixes it by behaving as if the range
was empty.

The new behavior is equivalent to the outcome of iterating
on a nil map or slice, and is useful because it allows
generic structures such as used in json (map[string]interface{})
to behave correctly if a key generally set to a list or map
isn't present.

R=golang-dev, r, gustavo
CC=golang-dev
https://golang.org/cl/4876046

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4895042

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4875048

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4901041

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4898042

R=r, rsc
CC=golang-dev
https://golang.org/cl/4873046

Since the posLink_url also adds a non-URL attribute, the quoting and  URL-escaping
must happen inside posLink_url (otherwise the non-URL attribute becomes part or the
URL portion of the tag.

R=r
CC=golang-dev
https://golang.org/cl/4888041

- rename template funcs for better consistency and
  sort them into groups of related functionality
- try to be more consistent with html vs url escaping

R=r
CC=golang-dev
https://golang.org/cl/4887041

- simplified pipelines
- simplified templates by using template variables
- converted most old-style formatters into new-style funcs
- fixed some escaping bugs (use of url escaping where it was missing)

R=r, dsymonds
CC=golang-dev
https://golang.org/cl/4868044

R=r, r
CC=golang-dev
https://golang.org/cl/4837071

R=r, r
CC=golang-dev
https://golang.org/cl/4837071

R=gri, dsymonds
CC=golang-dev
https://golang.org/cl/4881042

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4837048

func Reverse(*Template) *Template
returns a template that produces the reverse of the original
for any input.

Changes outside exp/template/html include:
- Adding a getter for a template's FuncMap so that derived templates
  can inherit function definitions.
- Exported one node factory function, newIdentifier.
  Deriving tempaltes requires constructing new nodes, but I didn't
  export all of them because I think shallow copy functions might
  be more useful for this kind of work.
- Bugfix: Template's Name() method ignores the name field so
  template.New("foo") is a nil dereference instead of "foo".

Caveats: Reverse is a toy.  It is not UTF-8 safe, and does not
preserve order of calls to funcs in FuncMap.

For context, see http://groups.google.com/group/golang-nuts/browse_thread/thread/e8bc7c771aae3f20/b1ac41dc6f609b6e?lnk=gst

R=rsc, r, nigeltao, r
CC=golang-dev
https://golang.org/cl/4808089

R=golang-dev, dsymonds
CC=golang-dev, mikesamuel
https://golang.org/cl/4875042

R=r
CC=golang-dev
https://golang.org/cl/4878042

How quaint.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4874045

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4868045

- first step; rough conversion of all template files
- there is plenty of opportunity for cleanups/simplifications (next CLs)
- html and text output as before

R=r, dsymonds
CC=golang-dev
https://golang.org/cl/4852048

This continues the work in revision 914a659b44ff, now passing more test
cases. As before, the new tokenization tests match html5lib's behavior.

Fixes #2124.

R=dsymonds, r
CC=golang-dev
https://golang.org/cl/4867042

Also simplify nil handling in printing.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4869042

IMPORTANT: Previous usage of *Files will continue to compile
fine but misbehave since the interface is compatible.

The following functions have been renamed:

    ParseFiles => ParseGlob
    ParseFile => ParseFiles
    ParseSetFiles => ParseSetGlob
    ParseSetFile => ParseSetFiles
    ParseTemplateFiles => ParseTemplateGlob
    ParseTemplateFile => ParseTemplateFiles

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4867041

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4859042

Not sure how to detect read-only but at least
this pins the blame on the hg server.

R=r, bradfitz
CC=golang-dev
https://golang.org/cl/4847053

R=bradfitz, dsymonds, fshahriar
CC=golang-dev
https://golang.org/cl/4859043

Also protect against invalid (zero Value) reflect.Values.

R=rsc, gri
CC=golang-dev
https://golang.org/cl/4810094

Fixes #2140.

The http.DefaultTransport's RoundTrip method leaves the http.Request object
in an altered state after performing the round trip.  This patch removes
the header from the Request before returning to the client.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/4857041

R=rsc
CC=golang-dev
https://golang.org/cl/4855051

Addresses part of issue 2093
Thanks to espians....@

R=golang-dev, nigeltao
CC=golang-dev
https://golang.org/cl/4808087

- triegen.go: Factored out trie generation code from maketables.go
  (only renamed printTrieTables to printTables and made it a method).
- maketesttables.go: new tool to generate data for the trie unit test.
- Makefile: changed accordingly.
- trie.go: trie lookup code.
- trietest_data.go: generated by maketesttables.go.
- trie_test.go: unit test for trie.go.

R=r
CC=golang-dev
https://golang.org/cl/4844053

- triegen.go: Factored out trie generation code from maketables.go
  (only renamed printTrieTables to printTables and made it a method).
- maketesttables.go: new tool to generate data for the trie unit test.
- Makefile: changed accordingly.
- trie.go: trie lookup code.
- trietest_data.go: generated by maketesttables.go.
- trie_test.go: unit test for trie.go.

R=r
CC=golang-dev
https://golang.org/cl/4844053

Now that reflect has v.Addr(), we can use it.

R=golang-dev, dsymonds, r
CC=golang-dev
https://golang.org/cl/4860041

the format string does not specify its presence.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4839059

Every time we enter callback from Windows, it is
possible that go exception handler is not at the top
of per-thread exception handlers chain. So it needs
to be installed again. At this moment this is done
by replacing top SEH frame with SEH frame as at time
of syscall for the time of callback. This is incorrect,
because, if exception strike, we won't be able to call
any exception handlers installed inside syscall,
because they are not in the chain. This changes
procedure to add new SEH frame on top of existing
chain instead.

I also removed m sehframe field, because I don't
think it is needed. We use single global exception
handler everywhere.

R=golang-dev, r
CC=golang-dev, hectorchu
https://golang.org/cl/4832060

R=r
CC=golang-dev
https://golang.org/cl/4808088

R=r
CC=golang-dev
https://golang.org/cl/4830069

See https://golang.org/cl/4815087

R=golang-dev, nigeltao
CC=golang-dev
https://golang.org/cl/4849050

The additional token_test.go cases matches html5lib behavior.

Fixes #2124.

R=gri
CC=golang-dev
https://golang.org/cl/4844055

Fixes #2139.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/4838056

This addresses the biggest DoS in issue 2093

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4841050