fix installation on windows with vtk 6.1

During the install phase, it was looking for vtkCommon.dll in its old
location. Note that now this library does not exist anymore and the path
has been updated.
Fix compilation on mingw32
Remove a cmake warning with cmake 2.8.12 and up.

This remove the warning reported as:

CMake Warning (dev) in Utilities/gdcmopenjpeg-v1/libopenjpeg/CMakeLists.txt:
  Policy CMP0022 is not set: INTERFACE_LINK_LIBRARIES defines the link
  interface.  Run "cmake --help-policy CMP0022" for policy details.  Use the
  cmake_policy command to set the policy and suppress this warning.

  Target "gdcmopenjpeg" has an INTERFACE_LINK_LIBRARIES property which
  differs from its LINK_INTERFACE_LIBRARIES properties.

  INTERFACE_LINK_LIBRARIES:

    m

  LINK_INTERFACE_LIBRARIES:

This warning is for project developers.  Use -Wno-dev to suppress it.
allow flexible cross compilation testing
switch to mingw-w64 instead
Make it easier to find gdcmdata in cross compilation
Gcdm extracts some jpeg2000 pictures incorrectly

Fix bug 325 properly check that DICOM match encapsulated codec
Start adding missing md5sum