Adding leak hunter for running down SWT resource leaks
Track all Swt Resource subclasses, report totals

- tracks all known Swt::Graphics::Resource subclasses
- in addition to the count => backtrace report, also includes a
  class => total report
- adds tracking for resources that were disposed without being tracked.
  These seem to be all Swt::Graphics::GC objects. Probably these are the
  objects created by Swt (i.e. we didn't call .new on them), that we are
  not disposing ourselves.
Add backtrace report for untracked disposals
Move leak_hunter.rb to tooling directory
Merge pull request #682 from shoes/leak_hunter

Adding leak hunter for running down SWT resource leaks