Moved some typedefs to router.h and server.h, changed a few
constants to these enums. Renamed some types in config.h to
remove "Gateway".
There are still some functions in the public header which are
only used in core, but they seem to fit the theme of public functions
so were not moved.
When the relay master or external slave states change, they should be
ignored in the current implementation. When the relay master and slave of
external master events are added, the events can be enabled.
