Separating game-dev code from engine code - 1

[Nimac0]

Starting point: take out update() and init() from game.cpp into its own cpp -> goal is that there is a folder with everything we've programmed so far named 'engine' and one folder containing only the cpp titled 'dev' -> this new cpp has the same accesses as the original one (use same game.h) so all functions from engine are accessible -> there will be errors as there are some globals conflicting (see issue about fixing globals) -> once it is fixed in a way that it runs again as usual despite the refactor/split move on to step two of splitting (other issue)

[Nanogamer7]

Depends on #27

[Nimac0]

is done