Volume conversion and rendering (#350)

Add volume rendering features
 - Improve task runner
 - Improve reading from CDF files
 - Basic time varying volume rendering
 - Fix scaling bug in RenderableToyVolume

modules/volume/volumeutils.cpp

@@ -24,8 +24,9 @@
 
 #include "volumeutils.h"
 
-namespace openspace::volumeutils {
-    
+namespace openspace {
+namespace volume {
+
 size_t coordsToIndex(const glm::uvec3& coords, const glm::uvec3& dims) {
     size_t w = dims.x;
     size_t h = dims.y;
@@ -48,5 +49,6 @@ glm::uvec3 indexToCoords(size_t index, const glm::uvec3& dims) {
     
     return glm::uvec3(x, y, z);
 }
-    
-} // namespace openspace::volumeutils
+
+} // namespace volume
+} // namespace openspace