Merge pull request #1 from ptgreen/master

Small fixes to the LL(1) grammar, and a start on a LALR(1) bison grammar as a backup.
Streamline parsing of for/loop exprs, add parser-lalr to 'make check'
Address the interplay of prefix ops and expr-stmt juxtaposition in LALR grammar.
Add rparse, that runs rust mainline parser and dumps output AST as JSON.
Filter json objects a bit to minimize output.