Add basis of Parser class

Add members and constructor of Parser class.
Add is_eof() member
Add advance() member
Add current_type() member
Add current_string() member
Add make_snapshot() member
Add rewind() member
Add parse_symbol() member
Add parse_identifier() member
Add parse_type() member
Add parse_integer_literal() member
Add parse_character_literal() member
Add parse_string_literal() member
Add dependency for parser to Makefile.am
Add parse_translation_unit() member

Add also parse_function_definition() member declaration.
Add parse_function_definition() member

Add also following member declarations:
* parse_argument_list()
* parse_compound_statement()
Add parse_argument_list() member

Add also parse_argument() member declaration.
Add parse_argument() member
Add parse_compound_statement() member

Add also parse_statement() member declaration.
Add parse_expression_statement() member

Add also parse_expression() member declaration.