This class manages a buffer where all data usually stored in detection
plugin will get copied before unloading the plugin and starting the
game.
This class expects that two functions are present in every
GameDescription: sizeBuffer which calculates how many bytes we will need
to store the entry in RAM and toBuffer which copies the data in the
buffer and fix the pointers in the class.
At the end, it is expected that an ADDynamicGameDescription doesn't
depend anymore on data stored in the detection plugin.
The AD_GAME_DESCRIPTION_HELPERS macro allow to implement these functions
in all GameDescription which don't have any pointer except those in
ADGameDescription.
