isGridMaximized changed to isGridSemiMaximized and comment added about core...

isGridMaximized changed to isGridSemiMaximized and comment added about core handling fully maximized windows. Added assert to the else clause in restoreWindow, changed shifts to divide by 2 and added check for xwcm before calling sendSyncRequest. Also added an extra check so that we only call restoreWindow from stateChangeNotify if lastState was CompWindowStateMaximizedVertMask (e.g. not a fully maximized window incorrectly marked as isGridSemiMaximized).