- fix issue when removing class from system in Hierarchy window
- fiddle with categoery window
- hook up merge diff browse for git merge and mc merge
- remove TDMergerClientListElementBuilder and TDMergeTool
- TDMetacelloTool class>>priority for proper tool registration
- implement `git filetreetool` for doing diffs against filetree git repos ... two advantages:
  1. smalltalk source is formatted before comparison, so only semantic differences are shown
  2. senders/implementors menu items available on Smalltalk methods ...