Updated EditorMaterialSet and the default content for it
Fixed bad typo bug in GUIManager
Fixed GUISelectionBox public fields

Pulled material/texture out into a GUITexture
Changed GUIPanel stuff to use shared ptrs to GUIElement
Created EditorObject class and children (with non-committed files added to the project)

Represent individual elements of an editor panel

Project files also have EditorPanel.h/.cpp added but those files haven't
been committed yet because they aren't finished