Make offlineimap usage more robust

Use a different behavior when an already running offlineimap instance is
found.
The vaapi video extension doesn't work with multiple threads
Use a different key binding for postponing messages

The old one conflicted with the pgp options
Add new lists
Make it easier to deal with multiple accounts
Use a lower maxage
Include system-wide installed plugins
Purge unused channels from the autojoin list
Update plugin options
Use EwmhDesktops
Use st as the default terminal
Include the Russian keyboard layout
Remove the synergy configuration
Add an alias to clean xorg's clipboards