Removed some old craft
Migrated one regression test to pytest
Renamed test for direct rule call.
NoMatch memoization
memoization tests
Reworked comment support

Comments are now available as a comment list attribute on the parser
object.
Small performance fix
Default semantic action made optional.
Test for default semantic action
Fix in the parse tree reduction. Tests.
Fix in the bibtex example
Parse tree navigation using dot syntax + unit tests.
Small addition to parse tree navigation unit test.
Small change in debug message