Release version 0.2.3

Added

• Added override predefined symbol detection (yacc)
• Added predefined symbols to completion (yacc)

Changed

• Changed default value for rules region range (lex/yacc)
• Changed lex completion rule, now supports more cases (lex)
• Now keywords have different color (yacc)

Bug fixes

• Fixed wrongly detect regex quantifier {1, 2} as symbol (lex)
• Fixed missing error predefined symbol to yacc (yacc)
• Fixed escaped {}s detection (flex)