gnome-help: Empathy is dead. Hence replace it with Polari.

XChat is dead. Hence replace it with HexChat.
Mibbit does not offer GIMPnet in its dropdown. Hence remove it.

Fixes #73
1 job for master in 9 minutes and 28 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test
passed build-fedora #814713

00:09:28