xfce4-settings: add a 'Touchscreen pointer' option in mouse settings

'Touchscreen pointer' can be set per pointer device. If the pointer device gets
active (Press/Move/Plugin) and this option is set:

* Mouse cursor is hidden during normal operation
* When waiting for startup-notification a wait cursor is displayed
* The gtk2 setting TouchscreenMode is set to e.g disable prelighting buttons
  on mouse over

The changes are in use for a while now on my devices help using XFCE on
touchsreen devices.

The git-version of this patch series was sent to
https://bugzilla.xfce.org/show_bug.cgi?id=9474

 but no response was received
yet. In the patch series attached here the binary cursor files 'invisible' and
'wait' were taken out of patch 0001.. because the files were not created by
do_patch.

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>