* There is now a bool setting to turn off depth writing and testing for
RenderableSpheres (useful for background images).
* There is also an Option setting to choose blending mode, similar to
the setting that RenderablModel has.
* NOTE: The default behaviour for RenderableSphere have now changed.
Before it was always additive blending that was used but now it is
default blending that is used by default. If additive blending is
wanted, then use the option setting and select it instead.
* Split RenderableSphere class into a local and online sphere
* Make the video sphere derive from the regular sphere
* Make RenderableTimeVaryingSphere derive from RenderableSphere
* Some clean up
* Address PR comments
* Fade fixes
* Clean up RenderableSphere. Add orientation properties.
* Sane defaults for Digital Universe
* Clean up New Horizons related code
* Add basic scene
* Add ability to initialize rotation as quaternion and mat3
* Adapt legacy code to new Renderable interface
* Cleanup
* CMake cleanups
* Update current year
* Update copyright header
* Use script to return list of all modules
* Update credits, license and ghoul
* 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 initializeGL and deinitializeGL methods to OpenSpaceModule Call releaseAll from ProgramObjectManager in deinitializeGL to guard against errors when deinitializing assets
* Change removeProgramObject function in RenderEngine to take a non-owning pointer instead of a reference to a unique pointer to make it compatible with the ProgramObjectManager
Update Ghoul repository
* Using ProgramObjectManager in more modules to reduce the number of programs compiled at startup
* Implemented property animation mechanism
* Added easing functions to Ghoul and make them usable in animation
* Make sure that we don't leave properties around if SceneGraphNodes are deleted
* Adding opacity settings to base renderables
