Ignoring touch events generated by HW mouse

[gilnoh]

This is a patch for issue #114 .

• Since commit 6199841, HW mouse events are handled by GCMouse.
• However, HW mouse clicks still generate (additional) touch events. These touch events are then coming to and handled by touch handling code. This causes issues reported in #114, such as additional left clicks or jumping mouse pointers.
• In this patch, I added a small code that checks touch events for their origin. So it can ignore events from HW pointing device.
• Maybe there is a better way to handle this: For example, somehow disable mouse clicks from generating any touch event at all, would be a better way to handle this. However, I can't seem to find a way to do this.

[litchie]

Thanks for fixing this issue. Looks good

[gilnoh]

My pleasure!