Issue/24 (#549)

* Implemented property animation mechanism
 * Added easing functions to Ghoul and make them usable in animation
 * Make sure that we don't leave properties around if SceneGraphNodes are deleted
 * Adding opacity settings to base renderables

modules/base/rendering/renderablesphericalgrid.cpp

@@ -137,6 +137,9 @@ RenderableSphericalGrid::RenderableSphericalGrid(const ghoul::Dictionary& dictio
         "RenderableSphericalGrid"
     );
 
+    addProperty(_opacity);
+    registerUpdateRenderBinFromOpacity();
+
     if (dictionary.hasKey(GridMatrixInfo.identifier)) {
         _gridMatrix = dictionary.value<glm::dmat4>(GridMatrixInfo.identifier);
     }
@@ -210,6 +213,8 @@ void RenderableSphericalGrid::deinitializeGL() {
 void RenderableSphericalGrid::render(const RenderData& data, RendererTasks&){
     _gridProgram->activate();
 
+    _gridProgram->setUniform("opacity", _opacity);
+
     glm::dmat4 modelTransform =
         glm::translate(glm::dmat4(1.0), data.modelTransform.translation) * // Translation
         glm::dmat4(data.modelTransform.rotation) *  // Spice rotation