add touch event support for x11 server

[Yodoga]

Here is some code which will add support for x11 touch events. That way multi touch (only ten fingers) is also working under Linux.

[sgothel]

Thank you Danny, reviewing your pull request.
Excellent work.

The only issue I have is the usage of the static 'touch_coordinates' array,
which may lead to threading issues having multiple EDT threads on different X11 Displays running?

I will pull and merge your work and may add a fix to this.