Add improved ANTLR lexer adapter
Use the new lexer adapter implementation, greatly simplifying code
Refactor applyLexerState
If no current state is available, assume initial state
Make the operand of getLexerState clear by adding a parameter
Updated documentation for lexer classes
ANTLRv4Lexer requires tracking _ruleType as an additional state variable
Merge pull request #11 from sharwell/lexers

Lexer updates