Write version to configuration file.

This will be useful in the future--particularly for when we merge mpv_settings.
Further expanded the settings version functionality

Basically if the version is not recognized the player will load defaults/whatever it can find that is like the old settings. It will disable preferences and modification of settings--this way their settings file does not get littered with garbage.
Merge branch 'master' into mpv_settings

Conflicts:
	src/mpvhandler.cpp
	src/ui/mainwindow.cpp