BUG: Fix support for RLE-compressed & upper-left BMP.

Related to issue ITK-3199.

When reading an upper-left bitmap, the BMPImageIo class was returning
a region with a negative height.

The algorithm for reading RLE-compressed bitmap was not properly
implemented.

Change-Id: I8f02f18b4146b4d3005a0d1016074b847bc87689
Merge topic 'FixSupportForLRECompressedAndUpperLeftBMP'

a6e4d25 BUG: Fix support for RLE-compressed & upper-left BMP.