delete unused This() in preparation for removing linking via array indexes

R=rsc
DELTA=26  (2 added, 23 deleted, 1 changed)
OCL=16895
CL=16909

- more precise wording by having an explicit list of cases
- simplified statement list

R=r
DELTA=16  (10 added, 0 deleted, 6 changed)
OCL=16871
CL=16875

will move elsewhere when more complete.
parses, does not execute.
no character classes yet.

R=rsc
DELTA=522  (522 added, 0 deleted, 0 changed)
OCL=16863
CL=16874

R=r
OCL=16869
CL=16869

- language for selectors and array/map indices
- formal description of syntax notation used
- factor out common productions to better show
  symmetries in grammar

R=r
DELTA=113  (77 added, 13 deleted, 23 changed)
OCL=16853
CL=16865

R=rsc
APPROVED=rsc
DELTA=21  (21 added, 0 deleted, 0 changed)
OCL=16794
CL=16803

except in statement list, where it is expressed in words
- allow for empty import, const, type, and var decl lists inside ()'s
- fixed grammar for inc/dec statements
- added empty statement as it appears to be accepted by 6g

R=r
DELTA=75  (23 added, 21 deleted, 31 changed)
OCL=16785
CL=16785

R=gri
DELTA=8  (8 added, 0 deleted, 0 changed)
OCL=16765
CL=16767

suggested by rob (could make programs generating
go easier to write).

R=ken
DELTA=13  (13 added, 0 deleted, 0 changed)
OCL=16766
CL=16766

R=r
OCL=16720
CL=16728

R=r
OCL=16721
CL=16727

R=r
DELTA=6  (6 added, 0 deleted, 0 changed)
OCL=16726
CL=16726

R=rsc
APPROVED=rsc
DELTA=50  (4 added, 0 deleted, 46 changed)
OCL=16707
CL=16725

	- pointer to interface cannot have methods
	- record type names for better runtime error

R=r,ken
DELTA=85  (80 added, 0 deleted, 5 changed)
OCL=16658
CL=16722

R=r
OCL=16698
CL=16698

the parser accepts a bit more then it should)

R=r
OCL=16694
CL=16694

R=rsc
APPROVED=rsc
DELTA=1  (0 added, 0 deleted, 1 changed)
OCL=16688
CL=16690

- forward decls for interface and struct types
- complete & incomplete types
- optional semicolons

R=r
DELTA=216  (95 added, 15 deleted, 106 changed)
OCL=16465
CL=16687

R=ken
OCL=16651
CL=16653

R=gri,r
OCL=16648
CL=16652

	type T struct
	export type T struct { a int }

was not exporting T

R=ken
OCL=16650
CL=16650

R=r
DELTA=18  (18 added, 0 deleted, 0 changed)
OCL=16639
CL=16647

 *  1. all statements and declarations are terminated by semicolons
 *  2. semicolons can be omitted at top level.
 *  3. semicolons can be omitted before and after the closing ) or }
 *	on a list of statements or declarations.

now that semicolons are in, uncomment forward declaration
	of interfaces

R=ken
DELTA=285  (124 added, 114 deleted, 47 changed)
OCL=16638
CL=16646

 *  1. all statements and declarations are terminated by semicolons
 *  2. semicolons can be omitted at top level.
 *  3. semicolons can be omitted before and after the closing ) or }
 *	on a list of statements or declarations.

/home/rsc/bin/addsemi and then diff+tweak.

R=r,gri
OCL=16620
CL=16643

R=rsc
DELTA=7  (0 added, 0 deleted, 7 changed)
OCL=16600
CL=16630

	type T struct {
		next *T
	}

and

	type T *struct {
		next T
	}

are valid without needing forward declarations.

add "type T struct" syntax for forward struct declarations.

add "type T interface" syntax, but commented out
	(need to fix semicolons first)

R=ken
DELTA=452  (259 added, 115 deleted, 78 changed)
OCL=16580
CL=16584

R=gri
DELTA=4  (0 added, 3 deleted, 1 changed)
OCL=16565
CL=16579

R=ken
OCL=16550
CL=16550

type definition.

R=r
DELTA=3  (0 added, 2 deleted, 1 changed)
OCL=16537
CL=16545

R=rsc
DELTA=87  (37 added, 50 deleted, 0 changed)
OCL=16498
CL=16507

R=r
DELTA=7  (2 added, 2 deleted, 3 changed)
OCL=16495
CL=16499

R=r
OCL=16497
CL=16497

R=r
OCL=16494
CL=16494

R=ken
DELTA=2  (0 added, 0 deleted, 2 changed)
OCL=16489
CL=16489

R=ken,r
DELTA=86  (72 added, 9 deleted, 5 changed)
OCL=16488
CL=16488

R=r
DELTA=43  (43 added, 0 deleted, 0 changed)
OCL=16468
CL=16475

R=ken
OCL=16449
CL=16466

    package flag
	export type flag.Flag struct { name flag.string; usage flag.string; \
		value flag.Value; next *flag.Flag }
	type flag.string string
	type flag.Value interface { AsBool () (? *flag.BoolValue); \
		AsInt () (? *flag.IntValue); AsString () (? *flag.StringValue); \
		IsBool () (? flag.bool); IsInt () (? flag.bool); IsString () (? flag.bool); \
		Str () (? flag.string); ValidValue (str flag.string) (? flag.bool) }
	type flag.BoolValue struct { val flag.bool; p *flag.bool }
	type flag.IntValue struct { val flag.int64; p *flag.int64 }
	type flag.StringValue struct { val flag.string; p *flag.string }
	type flag.bool bool
	func (e *flag.StringValue) AsBool () (? *flag.BoolValue)
	func (e *flag.StringValue) AsInt () (? *flag.IntValue)
	...

the \ continuations are for this message, not real.

changed delimiter for import from (( )) to $$ $$.

replaced mksys.bash with mksys.c

changed sys.go to use leading export,
	fake package name is now SYS not foop

don't always require ; on forward func decls

R=ken,r
DELTA=1827  (446 added, 1083 deleted, 298 changed)
OCL=16433
CL=16463

R=r
OCL=16462
CL=16462

R=rsc
DELTA=32  (30 added, 0 deleted, 2 changed)
OCL=16440
CL=16445