ENH: Add option to write binary tensor files

Implemented writing out figer track VTK files in the
VTK binary format.  Added a test to compare a binary
file with the supposedly identical text file.

In the process added a dependency on VTK, in order
to use VTK readers in the file comparison program used
in testing.
COMP: Replace baseline vtk image

2T_fw_fiber.vtk baseline doesn't match current output.
I assume users think UKF is working correctly, and some
small algorithmic change is causing the mismatch
Merge pull request #1 from Chaircrusher/WriteBinary

ENH: Add option to write binary tensor files
ENH: Use VTK to write VTK files
BUG: replace baseline files with correct ones.

I enhanced the CompareFibers program to a) use VTK readers
and b) traverse the vtkPolyData objects returned and
actually compare all the fiber tracking data.

This actually broke the tests, because the files
generated by the current version of UKFTractography
has different data in them than the existing
baselines.  The actual fiber points are the same,
but the 'decorative' data is different.
ENH: Add a new test for writing out XML data files.

enhanced the test program to detect file type (just by the extension
so far) and use the appropriate reader type.
COMP: unified vtk file writing.

Use a single function to write out vtkPolyData
if the file extension is vtp, use the
vtkXMLPolyDataWriter.
ENH: Add ConvertVTK Utility

ConvertVTK will convert any VTK PolyDat file
in legacy or XML format to any other
VTK polydata format.
Merge pull request #2 from BRAINSia/FixVTKWriter

Fix vtk writer
COMP: fix warnings
Merge pull request #3 from BRAINSia/CompilerWarnings

Compiler warnings
ENH: make binary/compressed file writing the default

instead of -b (binary) and -z (compressed) flags, make

have -a (ascii) and -u (uncompressed).
COMP: fix warning
ENH: default to VTK XML file format for tracts files.
COMP: stop overriding passed in output directory CMake vars
Merge pull request #10 from BRAINSia/master

Improve file writing of UKF