JSON now properly parsed; added a debug function that dumps parsed JSON tokens.  Modifications to jsmn to make untouched/unmodified tokens easily detectable: exported new function `jsmn_mark_token_invalid`. Added and exported an in-place destructive token-to-string converter called `jsmn_stringify_token`. Use unsigned wherever we can. To do: mark non-public functions as static in gammu-json.c.