General overhaul of the Asset loading system

* Cleanup
* CMake cleanups
* Update current year
* Update copyright header
* Use script to return list of all modules
* Update credits, license and ghoul

Update Ghoul repository
Update SGCT repository

  * Make height map fallback layer work again
  * Add documentation to joystick button bindings
  * Removed grouped property headers
  * Add new version number constant generated by CMake
  * Make Joystick deadzone work properly
  * Change the startup date on Earth to today
  * Fix key modifier handling
  * Add debugging indices for TreeNodeDebugging
  * Fix script schedule for OsirisRex
  * Do not open Mission schedule automatically
  * Upload default projection texture automatically

  * General code cleanup
  * Fix check_style_guide warnings
  * Remove .clang-format
  * MacOS compile fixes
  * Clang analyzer fixes

Add PerformShading asset parameter for RenderablePlanet
Disable shading on default for Earth

* Add implementation of pure URL synchronization from foreign sources
 * Added hash of concatenated URLs to the identifier
 * Make the identifier optional
 * Remove unused code

 * Cleanup in Sync module
 * Correctly name mar097 asset name

Update Ghoul

Various cleanups

Update Ghoul repository
Remove libgdal link

Created new initialize method that gets called in OpenSpaceEngine initialize