* Use built-in toJSON converter instead of manually creating the string. Also removes the ability to create fisheye configuration files from the Lua script directly
* Move global objects out of OpenSpaceEngine
* General cleanup of main.cpp
* Add default_joystick asset to all scenes
* No longer suppress mouse interaction on slave nodes
* Window delegate uses function pointers rather than subclassing
* Fix for false overwriting of ImGUI configuration file
* Change default color and tilt angle of fisheye rendering
* Restructured performance manager
* Simplify screenshot handling
* Initial work to create SGCT configuration files from Lua
* More work on modularizing the SGCT configs
- Removing almost all pregenerated config files
- Working functions to create configurations with single and fisheye
rendering viewports
* Some more work on modular SGCT configurations
- Make more objects configurable
- Add documentation
- Make use of new `sgct.config.single` and `sgct.config.fisheye` functions
* Fix accidental commit
* Enable single configuration as default
* Do not remove single_fisheye.xml for inspiration
* Update single_fisheye.xml
* Update configuration_helper.lua
* Place multiview and multinode configuration files back
