Co-authored-by: Alexander Bock <mail@alexanderbock.eu>

The flag needs to be set for Mac users using clang as well

 * Add the ability to automatically generate code to extract values out of a Dictionary (see https://github.com/openspace/codegen

 for more information on how to use this)
* Applied this technique to a large number of cases in the codebase
* Don't add _codegen files to the repository
Co-authored-by: Emma Broman <emma.broman@liu.se>

General CMake cleanup/overhaul
* Enable precompiled headers for all projects
* Move specifications itto separate CMakeLists files
  * Add openspace-core as a subdirectory
  * Move handle_modules functionality into modules/CMakeLists.txt
  * Move handleapplications logic into apps/CMakeLists.txt
* Introduce openspace-module-collection interface library to simplify inclusion of modules in applications
* Turn module initialization into a two-step process to adapt to the new minimal dependency scenario
* Compile time speedup
  * Remove circular dependencies between modules and core preventing multithreaded compilation on MSVC
  * Build Spice multithreaded and as static library
  * Remove dependency from core to module-webbrowser
  * Remove unused dependency from kameleon
  * Remove additional unnecessary dependencies
  * Cleanup volume/kameleon/kameleonvolume modules
  * Fix visibility issues. Restrict include paths
  * Compile kameleon in parallel
* Other cleanup
  * O...

* Changes to work on Linux.
* Bring back AA Trail Lines on Linux.
* Included new branch with correction in cfitsio library linking.
* Updated SGCT
* Changes to compile in Clang on Linux.
Authored-by: Jonathas <jon.costa@gmail.com>
Authored-by: Tom Schober <tom@tomschober.com>

Merged maste. Changed code in multiple places to have the new memory pool working on linux (experimental yet).

Remove unused VLD code

Compile fix for scene.cpp

Fix for default.scene

Add initial Tracy profiling macros

Move AllowAddresses out of Interface into Server in openspace.cfg to circumvent potential stack corruption
Make lua_state not being copied

Instrumentation is disabled on default, but can be enabled in CMake