Merge branch 'master' of https://github.com/MediaPortal/MediaPortal-1 into MP1-4304-User_group_thumb_can_not_be_changed
Merge branch 'master' of https://github.com/MediaPortal/MediaPortal-1 into MP1-4304-User_group_thumb_can_not_be_changed
Merge branch 'master' of https://github.com/MediaPortal/MediaPortal-1 into MP1-2469-DetectDrive_method_obsolete
MP1-4088 : This patch adds the ability to use skin expressions, properties & functions in the onup, ondown, onleft and onright of all controls and in the hyperlink and action properties of GUIButtonControl.

Had to change some references to the protected fields from derived controls.
Merge remote-tracking branch 'remotes/upstream/MP1-2469-DetectDrive_method_obsolete' into 1.6.0Fork-BDJ
Merge remote-tracking branch 'remotes/upstream/MP1-4304-User_group_thumb_can_not_be_changed' into 1.6.0Fork-BDJ
Merge remote-tracking branch 'remotes/upstream/MP1-4088-BUG-Using_SkinSettings_Expressions_in_Hyperlink_Action_textcolor_and_OnLeft_right_up_down_not_possible' into 1.6.0Fork-BDJ