one for data requests and another for search requests
- add new handle member for max search retransmission
- set default maximum for search retransmission to one
- rename define for retransmission option
- remove global event function pointer
- add event function pointer to handle structure
- add handle parameter to register functions
- move all register functions to mbus-protocol-aux.c
- replace non standard u_char with unsigned char (ANSI)
- advice splint to ignore variadic macros
- move declarations from the middle to top of functions (C90)
- replace local library includes <> to ""
- changed local library file includes from <> to ""
- get rid of 'if (is_serial)' conditions
- mbus_context_serial() and mbus_context_tcp() allocates memory and initialize context specific function pointers
- simply mbus_connect() called instead of mbus_connect_tcp() or mbus_connect_serial()
- context specific data can still be accessed via (void* auxdata) pointer
- strdup(3) to copy host IP into TCP context struct
