Eliminate global methods
suite-sparse: update to 4.2.0

Update suite-sparse to the new 4.2.0. Remove the -DNCAMD workaround, since
this release includes upstream's fix for it. This should fix the recent Octave
build problems.
add option to disable tk as this breaks compilation.
Add keg only version 3 of ITK used for building VMTK
Add formula for vmtk

Add a formula for vmtk vmtk.org the Vascular Modeling Toolkit.
It depends on vtk and version 3 of the Insighttoolkit
Merge remote-tracking branch 'apjanke/suitesparse-4_2_0'