BUG: matplotlib is supposed to be optional

This code was failing to find matplotlib and
the first import was silently continuing, but
then the second call that requires matplotlib
began failing.
ENH: Add support for reduced SGEgraph on re-run

During the re-running of a workflow with SGEgraph, we can greatly
reduce the dependancies by determining which nodes have completed
prior to generating the submit-graph.

Job numbers need to be based on job ID's not on job names.  Job names are not unique.

BUG: Job names must be valid bash variables.
ENH: Adding new ants command line feature.

A newer version of ANTs has a command line feature
added that allows for more optimized processing in
multi-stage registrations.

ENH: Added new state saving interface to ANTs

In order to improve registration efficiency, it is important that
we can save and restore the state of a registration so taht
continuation may occur from a previous state.

ENH: Make transform writing mutually exclusive

Writing composite or non-composite transforms needs
to be mutually exclusive in the new version of
ants.