Editor

@kadst43 Going to go ahead and submit this for review since it is getting large.

Changes to game code:
- source/grid.js
  - Fixed bug with getting the grid coordinates from world position if 'this.minX' or 'this.minY' is not zero.
  - Fixed bug where 'validCoord' wasn't working if 'this.minX' or 'this.minY' is not zero.
- index.vwf.html
  - Linked to fileManager.js (unused)
- index.vwf.yaml
  - Fixed indentation
- source/gridObstacle.js (only used in editor)
  - Fixed bug preventing rotation from properly saving/loading
- source/fileManager.js (only used in editor)
  - Added ability to load/save files
- source/utils.js
  - Fixed bug in 'removeArrayElement'

Changes to editor:
- Added images for slider widget
- Added more UI elements
- Enabled shadows
- Added time of day lighting configuration
  - Automatically adjusts light color, direction, intensity, and shadow darkness based on hour inputted
  - Based on 24 hour cycle (mars day = 24hr 40m, so 24 was close enough and adds understanding)
- Started adding code to generate scenario files (still thinking about this one)
- Added save / load feature (currently only saves/loads environment and objects, no lights/scenarios/grids)
- Added new level button that clears the current level of all objects