Very early prototype of opengl visualizer
Added DataConverter class and basis for keyboard / mouse interactions
Added magnet dragging functionality
Introduced _win_to_world_coords function which converts window coordinates to world
Moved magnet radius to constructor variable
Refactored controller methods to new class
Added public 'redisplay_window' method in visualizer
Some changes to opengl drawing
Added auto rendering option
Correction to auto rendering
Merge branch 'feature-opengl-visualizer' into develop