Shorten default touch unblock delay and make it configurable

In order to protect ui from stray touch events mce blocks touch input
during display power up and after power up if fingers / palm are
touching the display. The touch input is unblocked after no touch has
been detected for unblock-delay ms.

Previously the unblock-delay was 200 ms. This was long enough for user
to make a double click to turn on the display and have mce eat away
the first swipe on the already visible ui.

Now the built in default is 100 ms. Different hardware adaptations can
use configuration files to override this. If needed, users can also
tune the value via mcetool --set-touch-unblock-delay option.

[mce] Shorten default touch unblock delay and make it configurable. Fixes JB#19833
Merge pull request #175 from spiiroin/touch_unblock_delay

Shorten default touch unblock delay and make it configurable