Bug fix for receiving invalid mouse wheel events

This bug fix *appears* to be necessary as a side-effect of the
refactored events handling subsystem of nomlib.
third-party/README.md: Bump used SDL library version up
Introduce third-party/build-deps.sh helper script
Update code-base to reflect recent API changes in nomlib

* nom::JsonCppSerializer interface has been removed -- deprecated
functionality is available through nom::JsonCppValue.
debug.hpp: Introduce TTCARDS_DEBUG_GAME_CONFIG preprocessor

* Disable the debugging unserialization output of GameConfig class.
GameConfig: Replace JsonCppValue with Value saving & loading

* (Finally!) Save functionality is once again restored.

* Introduce TTCARDS_DEBUG_GAME_CONFIG_LOAD &&
TTCARDS_DEBUG_GAME_CONFIG_SAVE preprocessors.

* Remove a bunch of old, obsolete code.