#95 warning window if writing to away/xa/dnd

[Anonymous]

per default gabber should warn you if you try to write
to away/xa or dnd users. especially dnd is often
ignored by some people.
it should be configurable for which of the three modes
this "warning window" will appear, but for dnd it
should be configured as default.

also in this context it would be nice if gabber would
ask the away/xa/dnd user for returning from away/xa/dnd
to online, if he attempts to write a message. this
should also be configurable for each of the three modes.