Implement the StkConverter.
Implement the StkConverter.

Makes some assumptions similar to the those of the TiffVolume
converter.  Still, it works for the sample dataset I was given and
a few others.  The notable exception is `zser24.stk', which is not
a scalar dataset -- Tuvok can't handle this in general, yet.

git-svn-id: 83c4c97093aeea62ac982fbfd516bf9db27f5c99@842 c36c8488-0289-0348-9b64-b301f74bd9a7

BlueBrain/Tuvok,BlueBrain/Tuvok,BlueBrain/Tuvok