Rebuilding M-Bus context structs in progress

- 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

mbus/mbus-protocol.c

@@ -13,7 +13,7 @@
 #include <stdio.h>
 #include <string.h>
 
-#include <mbus/mbus-protocol.h>
+#include "mbus-protocol.h"
 
 static int parse_debug = 0, debug = 0;
 static char error_str[512];