all type-specific value functions, and use ZeroVal to create
new frames.  Remove Value.Type; it was unused and difficult
for values with composite types.  Add Value.Assign methods.

R=rsc
APPROVED=rsc
DELTA=282  (135 added, 90 deleted, 57 changed)
OCL=31894
CL=31930

R=rsc
DELTA=5  (0 added, 0 deleted, 5 changed)
OCL=31900
CL=31900

Some cleanup.  Elem() on PtrType is now just Elem and matches
with ArrayType.  Generators now switch over the result type
instead of the operand type.  Delete unused diag function.

R=rsc
APPROVED=rsc
DELTA=281  (219 added, 18 deleted, 44 changed)
OCL=31876
CL=31891

R=ken
OCL=31890
CL=31890

R=gri
APPROVED=gri
DELTA=1  (0 added, 0 deleted, 1 changed)
OCL=31879
CL=31886

the n argument to strncat is the maximum
number of bytes to read from the src,
not the total size of the destination.

R=ken
OCL=31871
CL=31875

R=ken
OCL=31868
CL=31874

R=r
DELTA=1  (0 added, 0 deleted, 1 changed)
OCL=31863
CL=31870

- corresponding test cases
- some cleanups

R=rsc
DELTA=173  (68 added, 3 deleted, 102 changed)
OCL=31866
CL=31869

R=ken
OCL=31865
CL=31867

R=rsc
DELTA=68  (21 added, 28 deleted, 19 changed)
OCL=31857
CL=31864

make endianness explicit when writing values.

R=rsc
DELTA=129  (37 added, 7 deleted, 85 changed)
OCL=31826
CL=31854

R=rsc
DELTA=51  (41 added, 0 deleted, 10 changed)
OCL=31815
CL=31818

them as we go.

Lots of bug fixes.  Let the parser toss illegal character and
string literals.  Compile unary + correctly.  Allow float OP
ideal.  Compile unary * correctly.  Implement min and max float
values.

R=rsc
APPROVED=rsc
DELTA=64  (29 added, 7 deleted, 28 changed)
OCL=31811
CL=31814

R=rsc
DELTA=181  (93 added, 63 deleted, 25 changed)
OCL=31802
CL=31812

- code cleanup

R=rsc,austin
DELTA=28  (12 added, 2 deleted, 14 changed)
OCL=31808
CL=31810

   explicit.go:21:5: error: incompatible types in assignment (need explicit conversion)
   explicit.go:26:5: error: incompatible types in assignment (type has no methods)
   explicit.go:27:5: error: incompatible types in assignment (need explicit conversion)
   explicit.go:30:6: error: incompatible types in assignment (need explicit conversion; missing method ‘N’)
   explicit.go:33:7: error: invalid type conversion (need explicit conversion; missing method ‘N’)
   explicit.go:36:5: error: incompatible types in assignment

R=rsc
DELTA=1  (0 added, 0 deleted, 1 changed)
OCL=31805
CL=31807

R=gri
APPROVED=gri
DELTA=30  (25 added, 0 deleted, 5 changed)
OCL=31796
CL=31799

R=rsc
DELTA=130  (68 added, 6 deleted, 56 changed)
OCL=31798
CL=31798

literals and when the parser hits an unexpected EOF.  Also,
disallow newlines in character literals.

R=gri
APPROVED=gri
DELTA=23  (15 added, 1 deleted, 7 changed)
OCL=31790
CL=31797

excluding import data,
no yacc node has type Type* anymore.

0 reduce/reduce conflicts.

R=ken
OCL=31793
CL=31795

R=rsc
DELTA=337  (165 added, 119 deleted, 53 changed)
OCL=31786
CL=31794

R=rsc
DELTA=31  (8 added, 2 deleted, 21 changed)
OCL=31778
CL=31792

consts in the same factored block

	const (
		X = Y;
		Y = 2;
	)

R=ken
OCL=31782
CL=31782

R=rsc
APPROVED=rsc
DELTA=65  (29 added, 17 deleted, 19 changed)
OCL=31775
CL=31777

R=rsc
DELTA=113  (74 added, 14 deleted, 25 changed)
OCL=31776
CL=31776

R=rsc
APPROVED=rsc
DELTA=41  (0 added, 0 deleted, 41 changed)
OCL=31773
CL=31773

R=rsc
APPROVED=rsc
DELTA=689  (497 added, 169 deleted, 23 changed)
OCL=31755
CL=31772

introduce NodeList* type in compiler to replace OLIST.
this clarifies where lists can and cannot occur.
list append and concatenation are now cheap.
the _r rules are gone from yacc.
rev and unrev are gone.
no more lists of lists.

the representation of assignments is a bit clunkier.
split into OAS (1=1) and OAS2 (2 or more on one side).

delete dead chanrecv3 code.

delay construction of func types.

R=ken
OCL=31745
CL=31762

R=rsc
DELTA=11  (0 added, 0 deleted, 11 changed)
OCL=31760
CL=31760

R=rsc
DELTA=99  (32 added, 22 deleted, 45 changed)
OCL=31759
CL=31759

R=rsc
DELTA=20  (0 added, 12 deleted, 8 changed)
OCL=31758
CL=31758

- added a few TODOs

R=r
DELTA=4  (2 added, 0 deleted, 2 changed)
OCL=31751
CL=31756

R=rsc
DELTA=34  (33 added, 0 deleted, 1 changed)
OCL=31752
CL=31754

- still TODO: ignoring struct fields.

R=rsc
DELTA=309  (240 added, 2 deleted, 67 changed)
OCL=31750
CL=31750

- renamed Program -> SourceFile
- added Package node representing the AST for an entire package
- added filter function to create a source file mimicking the
  interface of an entire package

parser:
- parser entry to parse entire packages
- unified naming of parser entry points
- factored out entry points into new file (interface.go)

gofmt:
- extended to accept single .go files, and package paths:
  gofmt file.go	     	    // formatting of a single file
  gofmt -x file.go	    // interface of a single file
  gofmt -x ./MyPackage	    // interface of a local package
  gofmt -x math		    // interface of a $GOROOT relative package

Various adjustments in dependent files, documentation.

R=rsc
DELTA=634  (369 added, 153 deleted, 112 changed)
OCL=31743
CL=31748

R=rsc
DELTA=5  (0 added, 0 deleted, 5 changed)
OCL=31740
CL=31742

R=rsc
DELTA=15  (8 added, 2 deleted, 5 changed)
OCL=31738
CL=31738

considered running, so WaitStop doesn't lock up and
breakpoints get installed and uninstalled.  We also don't try
to detach from them, since that will fail.

R=rsc
APPROVED=rsc
DELTA=35  (26 added, 2 deleted, 7 changed)
OCL=31683
CL=31731

R=rsc
APPROVED=r
DELTA=146  (142 added, 0 deleted, 4 changed)
OCL=31654
CL=31716