Feature/CMake (#1443)

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
  * Only copy CEF files from one target (hard-coded to OpenSpace right now)
  * Remove unused instrumentation code
  * Remove the ability to render AABB for globes as it caused a circular dependency between GlobeBrowsing and Debugging
  * Removing compiler and cppcheck warnings
  * Turn almost all includes into non-system includes
  * Don't warn on deprecrated copy
* Updated submodules

modules/volume/rendering/basicvolumeraycaster.h

@@ -26,12 +26,9 @@
 #define __OPENSPACE_MODULE_VOLUME___BASICVOLUMERAYCASTER___H__
 
 #include <openspace/rendering/volumeraycaster.h>
-#include <openspace/rendering/transferfunction.h>
-#include <openspace/util/boxgeometry.h>
-#include <modules/volume/rendering/volumeclipplanes.h>
 
-#include <modules/volume/volumegridtype.h>
 #include <openspace/util/boxgeometry.h>
+#include <modules/volume/volumegridtype.h>
 
 namespace ghoul::opengl {
     class Texture;
@@ -42,6 +39,7 @@ namespace ghoul::opengl {
 namespace openspace {
     struct RenderData;
     struct RaycastData;
+    class TransferFunction;
 } // namespace openspace
 
 namespace openspace::volume {
@@ -78,8 +76,7 @@ public:
 
     void setVolumeTexture(std::shared_ptr<ghoul::opengl::Texture> texture);
     std::shared_ptr<ghoul::opengl::Texture> volumeTexture() const;
-    void setTransferFunction(
-        std::shared_ptr<openspace::TransferFunction> transferFunction);
+    void setTransferFunction(std::shared_ptr<TransferFunction> transferFunction);
 
     void setStepSize(float stepSize);
     float opacity() const;
@@ -97,7 +94,7 @@ private:
 
     std::shared_ptr<VolumeClipPlanes> _clipPlanes;
     std::shared_ptr<ghoul::opengl::Texture> _volumeTexture;
-    std::shared_ptr<openspace::TransferFunction> _transferFunction;
+    std::shared_ptr<TransferFunction> _transferFunction;
     BoxGeometry _boundingBox;
     VolumeGridType _gridType;
     glm::mat4 _modelTransform = glm::mat4(1.f);