For keys pressed in combination with Command, -[NSApplication sendEvent:]
simply doesn't pass the key-up event through to the window.  We have to
track which keys we've told Wine are pressed because Cocoa may consume
key-downs that trigger menus or system behaviors.

This reverts commit 0d20ac02.

As specified by the Windows Simplified Chinese Style Guide.

As specified by the Windows Czech Style Guide.

Spotted by Thomas Faber.