add notification support

[castorinop]

Support bash complete command notification. Use vte 2.91.

[linvinus]

first of all, thanks for patches, but it looks like this functional is unofficial , this function is absent in official documentation https://developer.gnome.org/vte/unstable/VteTerminal.html any way, i suggest to you to implement this patch as part of class AYTerm, in file altyo_terminal.vala

[castorinop]

hi, i rebase and move patch to altyo_terminal.