Moved changes from develop branch so python-cellframe can use JSON-RPC.
The following changes have been made:
- The handler_func_t callback signature has been changed, one more parameter has been added to it, namely const char *a_method. This is necessary so that in python-cellframe you can call the desired function, according to the method.
- The function signature has been changed so that btc_rpc functions can act as JSON-RPC request handlers, since the signature for the callback called by the handler json_rpc has been changed.
All changes have been carried over from develop.