Move handling of grave accent to inputhandler

It's a keypress that needs to be detected once, not a button that is
held and should have an effect every frame.
Remove primitives::generic

Was not used and incorrect (triangle fans?).
Simplify implementation of object visibility
Print locations of uniforms

Because we want to go with an older version of OpenGL to reach as broad
an audience as possible, and figuring out how to get the locations is
useful for that.
Switch shaders to glsl version 150

Instead of 330. Step towards lower OpenGL version requirements.
Move parts of main.cpp to init.h
Fullscreen added again
Added --fullscreen switch
Simplify FlagManager a bit

A mesh is stored and reused, not an object.
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/main.cpp