Don't check for pending event if no FCE listeners are configured

Eliminates one time() syscall for every AFP transaction.
From FR #78.
Add non timeout semantics which avoid extra calls to gettimeofday()

From FR #78.
Don't timeout when waiting for client requests

From FR #78
Remove size check that required a costly fstat()

In case the client request count plus offset is large then the file,
we're supposed to send the available data and set AFP error to
AFPERR_EOF.
No need to use an extra fstat() for that, we can also simply check
the whether the amount of data read from the file matches the
requested amount.

From FR #78.
Merge branch 'branch-netatalk-3-0' into develop
Add missing include, fixes bug #512
Merge remote-tracking branch 'origin/branch-netatalk-3-0' into develop