Revert "trigger modifier-only shortcuts when any modifier is released"
By default, xkeyboard-config maps shifted alt to meta, so kglobalacceld gets meta events instead of alt events:
- press Alt: Alt
- press Shift: Shift
- release Alt: Meta
- release Shift: Shift
The commit changed from tracking key presses to only using key releases, causing Meta to trigger when alt is released when shift is pressed.
Revert this change until we have a fix for #1.
This reverts commit 7a684018.