[Window Manager] make sure mixing effects for minimizing and mapping work together

In particular, make sure that the combination of desktop-effects-minimize-effect 'fade'
and desktop-effects-map-effect 'none' does not leave the restored window invisible.

This also takes care of the case where desktop effects are temporarily turned off when
restoring a minimized window, which could leave the restored window in a bad state.
Merge branch 'mapping-fix' of https://github.com/autarkper/Cinnamon into autarkper-mapping-fix

Conflicts:
	js/ui/windowManager.js
Merge branch 'master' of github.com:linuxmint/Cinnamon