Replaces clearRect with fillRect in AsyncImageDisplay.
Minor refactoring in GuiTestUtils.
Added GuiTestUtils.checkBlankImage
Added GuiTestUtils.checkNotBlankImage
Adjusted the paintDefault method of AsyncRenderingComponent.
Fixed some methods in AsyncRenderingComponent.
Removed unused method from AsyncImageDisplay.
Added repaint to AsyncImageDisplay.setInfLongRenderTimeout and AsyncImageDisplay.setLongRenderingTimeout.
Removed pointless check from AsyncImageDisplay.
Added lots of new test methods to AsyncImageDisplayTest.
Removed redundant method from GuiTestUtils.
Removed invalid check from AsyncRenderingComponentTest.
Fixed checkstyle violations.
Improved the cache test of AsyncImageDisplay.
Removed pointless code from AsyncImageDisplay.
Additional testing of transformations in AsyncImageDisplay.