Preliminary changes for Python
Merge branch 'master' of https://github.com/antlr/antlr4 into Preliminary-enhancements-for-Python-target

Terence's implementation
Improves the granularity of tests, thus helping narrow down differences
in behaviour between the reference Java target and other targets that
use the same test suite
merged preliminary python enhancements
cleanup after merge
Merge branch 'Preliminary-enhancements-for-Python-target' into Improved-tests-granularity
resolved the Lexer listener/visitor issue by changing the tests grammar
using @members to @parser::members
warningw to be fixed separately
Merge branch 'Improved-tests-granularity' into Preliminary-enhancements-for-Python-target
Oops, removed some unwanted changes
unwanted format change
Merge pull request #609 from ericvergnaud/Preliminary-enhancements-for-Python-target

Preliminary changes for Python