Working location for tests of Emacs::Run

 t/dat/
       src/
         templates/
            .emacs-*
         text
       arc
       tmp/
         html
         text
       home
       usr/
        lib*

  "src"  - source location for material that tests modify
  "tmp"  - output for generated files
  "arc"  - archive of reference copies to compare generated files to
  "home" - location for dummy user home directories
           contains .emacs files (generated from src/templates/.emacs-*)
  "usr"  - contains elisp library locations included in .emacs load-path settings