Fix issue #2 : Blurry text. Now the frame values of cells are integers.
Fix issue #2 : Blurry text.
Now the frame values of cells are integers.

chiahsien/CHTCollectionViewWaterfallLayout,tianxiao12345/CHTCollectionViewWaterfallLayout,iguchunhui/CHTCollectionViewWaterfallLayout,imjerrybao/CHTCollectionViewWaterfallLayout,lonelyplanet/TE-CHTCollectionViewWaterfallLayout,809848367/CHTCollectionViewWaterfallLayout,BlessNeo/CHTCollectionViewWaterfallLayout,SummerHanada/CHTCollectionViewWaterfallLayout,cstars135/CHTCollectionViewWaterfallLayout,809848367/CHTCollectionViewWaterfallLayout,goodheart/CHTCollectionViewWaterfallLayout,cstars135/CHTCollectionViewWaterfallLayout,imjerrybao/CHTCollectionViewWaterfallLayout,SummerHanada/CHTCollectionViewWaterfallLayout,tianxiao12345/CHTCollectionViewWaterfallLayout,iguchunhui/CHTCollectionViewWaterfallLayout,boherna/CHTCollectionViewWaterfallLayout,BlessNeo/CHTCollectionViewWaterfallLayout,goodheart/CHTCollectionViewWaterfallLayout,chiahsien/CHTCollectionViewWaterfallLayout