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 gnome-3-36 in 12 minutes and 31 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #814714
build-fedora

00:12:31