Fix comment style for SetTransferSyntaxUID.
Get SOPClassUID from meta-header if not in data set.

This is specifically for the sake of DICOMDIR data sets, where
the meta header is the only place that the SOPClassUID for the
DICOMDIR exists.
BUG: Don't count LengthToEnd element when computing size.

The LengthToEnd element is retired and vtkDICOMCompiler removes
it if it is found.  Therefore, neither should it be counted when
the group length is computed.
Keep the LengthToEnd if it was already present.

This was the only retired tag that was forcefully stripped from the
data set.  If present, it seems better to ensure that it is correct,
than to remove it.  This also makes it easier to pass through old data
sets unchanged.
Don't write bogus tags with group < 0x0002.
Keep the private information in the meta header.

Even though we re-create the meta header, it makes sense to keep the
private information unless we have new private information to replace
it with.
BUG: RLE codec was using big-endian ordering for 16-bit data.

The RLE segments start with the most significant byte and end with the
least significant.  On a little endian machine, this means starting with
the byte that is at the highest address.
Ensure that RLE codec works on big-endian machines, too.
Add a fallback for when PixelSpacing is zero.

It should never be zero, but just in case, set it to 1.0 if it is.
Minor comment fixes to vtkDICOMImageCodec.
Add missing "stddef.h" include for ptrdiff_t.
Fix warnings generated by MSVC.
Bump the version number to 0.5.0.

The major changes since 0.4.5 are as follows:
- Various cmake improvements, including CDash support
- The reader provides a vtkMedicalImageProperties object
- DICOM dictionary updated to the 2013 standard
- Resolution of private tags based on creator info
- niftitodicom supports RGB (for secondary capture only)
- native RLE codec (use DCMTK or GDCM for other codecs)
- API for vtkDICOMValue has been updated
- new vtkDICOMFile class allows utf8 paths

The API changes to vtkDICOMValue are as follows:
- GetNumberOfValues returns a size_t value, not unsigned int,
  and values with encapsulated data can now be > 4GB in size
- Methods that used to specify a range of values via a start
  and end pointer, now use a start pointer and a size
Add some support for functional groups and enhanced MR writing.