Move shaders into their correct modules

Add path determination to modules that automatically sets correct path resolve tokens

modules/volume/volumemodule.cpp

@@ -33,7 +33,14 @@
 
 namespace openspace {
 
+VolumeModule::VolumeModule() {
+    setName("Volume");
+}
+
 bool VolumeModule::initialize() {
+    bool success = OpenSpaceModule::initialize();
+    if (!success)
+        return false;
 
     auto fRenderable = FactoryManager::ref().factory<Renderable>();
     ghoul_assert(fRenderable, "No renderable factory existed");

modules/volume/volumemodule.h

@@ -31,6 +31,7 @@ namespace openspace {
 
 class VolumeModule : public OpenSpaceModule {
 public:
+    VolumeModule();
     bool initialize() override;
 };