Implement a hack for right- and middle-buttons on weird tablet devices

If should fix the following cases:

1) Wintab drivers that do not generate tablet events for right-click and
   middle-click.

2) WinInk mode. With the patch both right- and middle-clicks should be
   available with the stylus buttons.

To activate a workaround just add the following to your 'kritarc':

rightMiddleTabletButtonWorkaround=true

This hack just ignores tablet events for right- and middle-click and
starts to use mouse events for them. Please be careful, the hack will
make right- and middle-strokes less precise. And it also can just break
the tablet support completely.

CCBUG:399585
CCBUG:368849