Add goimapnotify for push notifications

[CarlosLoboxyz]

I receive instant confirmation codes from my bank all the time, using the cron daemon was not a good suit for me because of the waiting time, so i came across this simple program which does exactly what i was looking for and makes mutt behave more like a modern email alternative, hope you like it. :wink:

[appeasementPolitik]

Really cool, works very well on my system. I never even knew instant email was possible. One small issue that I found in the PR, line 15 of mw:

imapnotify="${XDG_CONFIG_HOME:$HOME/.config}/imapnotify", should become imapnotify="${XDG_CONFIG_HOME:-$HOME/.config}/imapnotify". It's missing a dash.