* Remove old non-submodule version of nlohmann in favor of submodule
* Update nlohmann from 3.9.1 to 3.12.0
- Already disable implicit conversions in preparation for next major version
* Separate layers for the Moon and Earth
* One asset each for each server, New York, Utah, and Sweden
* Add the layers asset files for Earth and Moon
* Add new layers structure for Mars and Europa
* Add layers assets for Mercury and Enceladus
* Add more layer assets for all servers
* Add layer assets for each server on the top asset level
* Rename Venus Utah cloud combo layer asset (breaking change)
* Clean up layer asset descriptions
* Update layer asset version name
* Fix base layers error
* Add configuration option to choose layers server
* Add Lua functions to access configuration settings
* Extend configuration Lua function
* Add layer server setting in setting gui + add 'None' as a server option
* Add base layers when server 'None' is used
* Add tests for the new Layer Server setting