pylangparser: re-implemented token matching mechanism used by Lexer

Previous mechanims could not handle certain cases shuch as matching
specific words like "\"text\"" when there were no other token matching
"\"t, "\"te, "\"tex and "\"text.
gtk_doc_parser example: initial version
sql_parser example: fix grammar according to new Lexer algorithm
simple_calc_language: fix grammar according to new Lexer algorithm
simple_calc_custom_ast: fix grammar according to new Lexer algorithm
c_lexer: fix grammar according to new Lexer algorithm
c_parser: fix grammar according to new Lexer algorithm