Added an about dialog for the tomviz application

This adds some basic version information, logos, links to the web
site, and credits the principal developers and funding source.
Added a few links in the text of the about dialog
Merge branch 'about-dialog'
Make sure we link accelerated libraries against tbb.

This was working before, because the version of VTK we linked too, was
built with SMP enabled and set to TBB.
Merge branch 'tbb_linking'