COMP: Make FindDCMTK more verbose

It will display the following text:

-- Trying to find DCMTK expecting DCMTKConfig.cmake
-- Trying to find DCMTK expecting DCMTKConfig.cmake - failed
-- Trying to find DCMTK relying on FindDCMTK.cmake
-- Trying to find DCMTK relying on FindDCMTK.cmake - ok

Adapted from commontk/CTK@2ac36d10ec

Change-Id: Ia04e091ad47ee00e238c7c910ee750b4efb89484
DOC: Improve FindDCMTK.cmake documentation

Adapter from commontk/CTK@33ade88b

Change-Id: I4b59127db20224ef40cb67c7b372e8a59f04821c
COMP: Ensure DCMTK libraries can be found on system without setting DCMTK_DIR

See inlined comment for more details.

Change-Id: Id6efee7eee301b73cbeec59f9739fb9f6450baf5
COMP: FindDCMTK - Workaround bug in packaging of DCMTK 3.6.0 on Debian.

See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=637687

See inlined comment for more details.

Change-Id: I2920c7c28a5984fe7fa750f491de2b4fa8dda8f6
COMP: Update ITKDCMTK_EXPORT_CODE_(BUILD|INSTALL) to support system DCMTK

This commit ensure version of DCMTK with or without a DCMTKConfig.cmake
file could be found.

For more details about the two different versions of DCMTK, refer to the
comments in FindDCMTK.cmake (as of d903483).

Change-Id: Ibd0cccf3774ac4177aec7f238283342a185d7d40
COMP: FindDCMTK - Exclude -D from DCMTK_DEFINITIONS for easier re-use

Since target properties like COMPILE_DEFINITIONS
or INTERFACE_COMPILE_DEFINITIONS do not expect definition to include "-D",
this commit exclude it from definition list associated
with DCMTK_DEFINITIONS.

Change-Id: Ia59922d6efd9deda1c0e4afbfbd010f5f77935ea
Merge topic 'fix-building-against-system-dcmtk'

361d2ea COMP: FindDCMTK - Exclude -D from DCMTK_DEFINITIONS for easier re-use
1f84205 COMP: Update ITKDCMTK_EXPORT_CODE_(BUILD|INSTALL) to support system DCMTK
04ee8cf COMP: FindDCMTK - Workaround bug in packaging of DCMTK 3.6.0 on Debian.
1c2253c COMP: Ensure DCMTK libraries can be found on system without setting DCMTK_DIR
d903483 DOC: Improve FindDCMTK.cmake documentation
d761250 COMP: Make FindDCMTK more verbose