Ui fix: Correct drag modification of timeline on pointer (mouse) devices, and add support for drag modification on touch devices.

This fixes a bug where a fast drag across the timeline on pointer devices would leave 'holes' in the modifies period. In addition touch support was added to allow the same kind of modification on touch devices (ie smartphones/tablets). There is still an issue where this does not work in the openHAB BasicUI opened in Safari on iPhone, but this is probably an issue with the enclosing html. It has been tested successfully on iOS Safari with the new MainUI OH3 widget.