make-it-so.el: remove `mis-file-names'
make-it-so.el: move to file-stored sources and targets

* make-it-so.el (mis-target-files): Remove.
  (mis-make-it-so): Simplify.
  (mis-abort): Use files.
  (mis-finalize): Use files.
  (mis-replace): Use files.
  (mis-action): Use files.

Using files allows multiple simultaneous projects.