Allow function statements everywhere

Cleanup parsing of blocks
Parse labels
Merge pull request #55 from cesanta/fix_function_statements

Allow function statements everywhere
Merge pull request #56 from cesanta/labels

Parse labels
Ensure that tests not saving the AST

Previous commits included `SAVE_AST 1` by mistake.
Merge pull request #59 from cesanta/fix_save_ast

Ensure that tests not saving the AST
Added --dump-binary-ast cmd option