Add support for absolute positioning pf the mouse cursor

[antman2]

Hi,
I've crafted a crude patch demonstrating how to use absolute positioning of the mouse cursor.
This is useful in games like Torchlight where you'd normally use the mouse to click somewhere in the playfield to set the PC's destination.
This patch also includes the project file upgrade for Xcode 7 (as a separate commit).
Thanks and kind regards,
Anthony.
patch-mouse-absolute.zip