Update code to latest API in nomlib's feature/GUI dev branch

* Use new states management interface
Introduce GameEvent::NUM_EVENTS enum value
Fix couple issues

* Use bitmap font for choice labels; was defaulting to Arial.

* Use DEBUG logging priority for NOM category messages; this
enables showing logging generated by usage of the NOM_DUMP macro.
Update codebase to use deferred states management

This corrects the crash that results when trying to change state
from within a callback from a nom::UIWidget event.