Git hygiene

Marked .DS_Store files as ignored
add basic code generation testing rig and 1st test.
Fixes #554
Merge pull request #566 from parrt/args-as-templates

Args as templates
add toString so profiler can print out later
Merge branch 'atn-profiler' into 4.2.3-dev
have to copy original token index over as well to transformed token.
Merge branch 'master' into 4.2.3-dev
Merge branch 'atn-profiler' into 4.2.3-dev
any block within transformed left-recursive rule gets "grammar region" map to entire original rule.