change stage1,stage2,stage2 into not(stage0)

With luck, this will allow rust to compile itself without --cfg flags again...
refactoring mod.rs
parser comments only
refactor parse_fn_decl
syntax test cases now pass
adding parse_path
simplify, based on invariant that items_allowed != foreign_items_allowed
remove unnecessary function
reindent in parser
get rid of prec.rs

prec.rs no longer had much to do with precedence; the token->binop
function fits better in token.rs, and the one-liner defining the
precedence of 'as' can go next to the other precedence stuff in
ast_util.rs
comments
top-of-file comment for syntax.rc
parser comments
refactoring
refactoring to split foreign_items from items
continued refactoring
removed old type dispatch test
parser refactor to separate foreign items
continued refactor
dead code check