completed color management implementation

This commit adds the background functionality of the render cache invalidating
whenever a footage's color space is changed. This includes when the project's
configuration is changed as well.

app/project/item/item.cpp

@@ -21,7 +21,8 @@
 #include "item.h"
 
 Item::Item() :
-  parent_(nullptr)
+  parent_(nullptr),
+  project_(nullptr)
 {
 }
 
@@ -127,6 +128,18 @@ const Item *Item::root() const
   return item;
 }
 
+Project *Item::project() const
+{
+  const Item* root_item = root();
+
+  return root_item->project_;
+}
+
+void Item::set_project(Project *project)
+{
+  project_ = project;
+}
+
 bool Item::CanHaveChildren() const
 {
   return false;