bevy backend + texture parsing

Changes

• rewrote with bevy rather than my custom crappy rendering backend
• less aggressive updating (will just notify you of new versions)
• finally parse materials and textures and display them (not guaranteed to show correct textures)
• massively improved the feel of moving, rotating and scaling actors
• mouse picking actually uses raycasts so you can directly click meshes

Full Changelog: 0.12.0-alpha...0.13.0-alpha