Unmount ISO for external movie player and check for nullorempty (Guzzi fix)
add Thumbnail to (re)add folder display for #selectedthumb
Merge remote-tracking branch 'remotes/origin/BUG-4170-Using_External_Player_prevents_Virtual_Drive_unmounting'
Merge remote-tracking branch 'remotes/origin/BUG-4174-selectedthumb_no_longer_displays_default_folder_icon_in_RecordedTV'
Merge remote-tracking branch 'remotes/upstream/master' into 1.3.0Alpha_SEB_ADDONV3_HomeY

Conflicts:
	mediaportal/Core/Player/g_player.cs