Clean up ContinueMenuState GUI events somewhat

* Update code to reflect changes in nomlib's API -- ::pop_state to
::pop_state_resume.

  ContinueMenuState:
* Rename event callback methods in to better reflect
their scope.

* Change starting position of cursor & question answer selection
(from YES to NO).

* Clean up on_gui_* methods a bit (use widget data as much as possible).
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.
Update code to use renamed state methods

nomlib branch feature/GUI
Update code to use LogPriority::NOM_LOG_PRIORITY enum values
Refactor input subsystem to use nom::InputMapper feature

The entire game has (finally!) been moved 100% over to a run-time
configurable action binding input subsystem. This change greatly
simplifies the events handling logic and reduces duplication
considerably.

* Joystick input handling has been implemented in every state now.

* Modifying card rank values no longer exhibits the cursor hopping bug,
due to clean up of InputStateMapper in nomlib.

* A couple other minor improvements that I can't think of at the
moment... (ContinueMenuState && GameOverState is all that comes to
mind...)

* debug.hpp: Introduce TTCARDS_LOG_CATEGORY_EVENTS enum value.
Fix CMake Policy CMP0048 warning (version vars)

...regarding the usage of the reserved PROJECT_VERSION variables. I've
chosen to opt out (use old, pre-3.0 CMake behavior).