sock_util used ot check RIOT_VERSION for selecting fmt functions.
RIOT's Makefile.dep sets fmt as a dependency for sock_util,
so the usual MODULE_FMT can be used.
One special case less.
If a new event is fired during the execution of the event callback,
`event->type` might change. However as `event->type` is set to 0 after
the execution of the callback, that leads to it being 0 on the next
round of the event handler's execution, leading in the event getting
lost.
Add additional checks to the port number parsing in str2ep to validate
the port number supplied in the string. This only verifies that the port
number is no longer than 5 chars and the resulting number fits in a
uint16_t.
It is still possible to supply up to 5 random chars.
URLs without a path were treated as invalid, while according to the URL
specification they are valid
Also fixes a missing null terminator in the returned path