Until we're able to detect touchscreen itself, let's have a detection
based on a form factor of the device.
Tablets and handhelds are usually equiped with touchscreens, so as a
default enable touchscreen GUI there.
- Windows and Linux supports autodetection.
- Android is hardcoded as touch-based.
- MacOS staying same as before without detection.
Signed-off-by: David Heidelberg <david@ixit.cz>
Also remove the now useless options (like IRRLICHT_INCLUDE_DIR)
and update download instructions, CI and similar.
Co-authored-by: sfan5 <sfan5@live.de>
