COMP: Fix compiler warnings with ITK_USE_SYSTEM_VXL

Commit 41793b40 attempted to solve an unused variable warning by forking
VXL. The warning was still triggered when ITK_USE_SYSTEM_VXL was enabled.

This reverts the fork of VXL and solves the warning when using system VXL
too.

Change-Id: I61db91d3269818a4819541dc5ec6a25d273f3dd2
BUG: Tiff compression was broken and untested

A user reported receiving the error:
JPEGLib: Bogus input colorspace.
while trying to use JPEG compression witk TIFFImagio.

This was not covered and apparently never tested.

This patch fixes the erro and adds tests for each compresion option
for grayscales and RGB imagaes.

Also, a Warning message is substitued for a Debug message if LZW
compression is selected.

Change-Id: Iba27f4e553a427755b9a1bf2f2aa435a120242e5
Merge topic 'Bug_TIFFImageIO_Compression'

13331ca BUG: Tiff compression was broken and untested
Merge topic 'VNL-Diag-Warning'

0cfabd0 COMP: Fix compiler warnings with ITK_USE_SYSTEM_VXL