Added cmd args parsing. Fixes and improvements. - Added parameter to load files from command line - Added parameter to specify window size from command line - Added new themes. Default theme is chosen to try to match OS's. - Mapped key "equal" to zoom-in as well. - Fixed crash when pressing icon toogle buttons (trace orbit and AA buttons) - Fixed crash when creating a new universe or loading one. - Fixed error on file extensions shown in FileDialog. - Fixed glitch when changing directory in the save dialog. - A lot of refactoring