prevent the right way bad show to crash us; add comment on special treatment of show is None in *status events

updated pot/po files

plz don't ask questions in the code
I put that here cause this function is called when we log in and never after

history window now marks progressively days that have logs in selected month (thanks to gtasklets/pseudo-threads idea by the great Gustavo)

update the value of the status combobox when we go invisible and cancel because of the groupchat warning, or when there is no synced with golbal status account