Release version 0.2.0

Added

• Added lex/yacc parsers and language services
• Added feature: basic diagnostics support (lex/yacc)
• Added feature: rename symbol support (lex/yacc)
• Added feature: find references support (lex/yacc)

Changed

• Architectural changing, now uses language service pattern
• Better completion handling/detection (lex/yacc)
• General optimization
  • parsing time 3x less than before
  • binary search to detect C code region, computation time reduced from O(n) to O(log(n))
• Updated README.md