to avoid segmentation faults, out of bounds access and integer overflow
make parseable for splint
suppress splint warnings about datatype cc_t
fix type of return value for read()
add checks before accessing tty
- 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
