Get VisTrails patches in VisTrails master

[remram44]

A lot of changes went into VisTrails's dat branch. These should be rebased on top of current master, checked and simplified, and get into master after review.

• Rebase on top of VisTrails's master: dat_/rebase
  • This took a long time! 173 commits on DAT (117 without merges), 1746 commits on master (drifted apart for 2 years!)
• Simplify (i.e. collapse successive changes into actual patches)
  • This is actually a lot of work because a lot of changes occurred during DAT's development. Package id changed, we moved from pylab to matplotlib packages, the tabledata package was even originally a DAT component.
• Check that both DAT and VisTrails work; make sure the hooks are everywhere, the spreadsheet works, etc
• Get it into VisTrails
  • Fixes: Fixes from DAT VisTrails#1077
  • Changes