Formatting, minor fixes and yajl_parse_integer optimized

Additional notes:
 - `yajl_lex_current_line`, `yajl_lex_current_char` and `yajl_lex_peek` seems to be unused and unsupported.

 - https://github.com/lloyd/yajl/blob/fcfff36b3bacec948ca5292f5191bcbcd52a5266/src/yajl_lex.c#L306 this break from the loop differs from all others, which are `goto finish_string_lex;`, it is suspicious.