core: Drop InputDevice::TabletEventType
It is very inconsistent in comparison to the rest of InputDevice. Other event types are specified using the signal type.
This change drops the TabletEventType enum to make the InputDevice API more consistent. Unfortunately, it results in a bit of code duplication, but on the bright side, such a design makes it clear what data you could expect from the input device.
Edited by Vlad Zahorodnii