Update to the final release of ANTLR 4.2
antlr4-runtime depends on antlr4-annotations
Work around ANTLR 4 issue 461
Remove the Go to Match Transition and Go to Rule Reference commands from the parser debugger navigator context menu since they are not yet implemented
Highlight syntax errors in the parser debugger (fixes #24)
Highlight syntax errors in the navigator (fixes #23)
Fix lexer rules not showing in navigator for combined grammar (fixes #28)