[Editor] Minimap

* Added MiniMap class
* Added UiQuad class
* Slightly larger world
* Getter for Block type
* Fixed Cell::getBlock by translating the coordinates to cell local space
* Added getter for Cell position
* Using Vecs instead of x,y,z in many places
* Editor cursor now a simple vector, create the renderable in the render loop
* Added ortho projection support to graphics
* Minimap rendered when in help active mode. Minimap us updated by pressing
  'm' for performance reasons.
* Added a lot of glGetError() asserts in Graphics
* Added Graphics::scale
* Added Graphics::generateTexture and Graphics::setTextureData for
  changing texture contents on the fly
* - and / operators for Vec2i
* Added World::getBlockAt for convenience
* Added World::getMinCoordinate and World::getMaxCoordinate