GUIEpgGridContainer: split Render() into Process() / Render()
GUIEpgGridContainer: get rid of GetRulerCacheOffsets() method which is just duplicated GetProgrammeCacheOffsets()
GUIEpgGridContainer: get rid of unused now (and never should be used) m_renderTime
GUIEpgGridContainer: fix memory freeing for ruler items
GUIEpgGridContainer: fix memory freeing for programme items
GUIListItemLayout: SetWidth() / SetHeight() - mark invalid only when new size is different from old one
Merge pull request #2603 from pieh/epggrid_dr

GUIEpgGridContainer: add dirty region processing and fixes for missbehaving memory freeing