Some updates to everything

Here's a brief rundown on what this update includes:
- **Heatmaps can now be shown in union (options to 'Show' and 'Show Only')**
- **State can be saved with export to URL (under Export -> Share Link -> URL). This includes map center, zoom level, markers placed, and data showing**
- **Fixed a major bug in hydro power generation pre-processed values where streams found and magnified the highest nearby value**
- Improved appearance of multiple data types loading; screen draws only occur when all are ready
- Added checks in to cancel a query in progress if it has been superseded
- Fixed bug where using the location bar to go to a new place while a heatmap is toggled on would crash the script
- Fixed bug where creating a marker near the top of the screen could create an info window that would jump the map, but not refresh the heatmap
- Fixed bug where interpolated data could significantly change when panning
- Fixed bug where heatmap would exhibit tearing at far northern latitudes
- Updated legend image
- Modified thresholds for solar and wind energy and marker images