OutOfBoundsMirrorFactory: fix javadoc
Remove duplicate ScreenImage implementation

Both UnsignedByteScreenImage and ByteScreenImage provide a ScreenImage
implementation based on UnsignedByteType data. But ByteScreenImage
extends ArrayImg which reduces the amount of boilerplate code.
Add new DataBuffer types: int8, int16 and uint32

These classes were originally implemented as part of Bio-Formats
(http://openmicroscopy.org/site/support/bio-formats). The code then
migrated to the SCIFIO project (http://scif.io/), and finally upstream
to ImgLib2.

Signed-off-by: Curtis Rueden <ctrueden@wisc.edu>
Rename ByteScreenImage and ShortScreenImage

Firstly, they are actually UnsignedByte and UnsignedShort, respectively.
Secondly, they are specifically AWTScreenImage implementations, since we
generalized ScreenImage to also support non-AWT scenarios (in theory).
Add superclass for ArrayImg-based AWTScreenImages

Both UnsignedByteAWTScreenImage and UnsignedShortAWTScreenImage are now
much shorter, as the bulk of the code is inherited from the superclass.
Add more ArrayImgAWTScreenImage implementations

The following types now exist:
* Byte
* UnsignedByte
* Short
* UnsignedShort
* Int
* UnsignedInt
* Float
* Double