Allow patchers to process records added to patch by earlier patchers.

[mrudat]

• Adds the target patch file as an input file to all patchers targeting that file.
  • This should only add the target patch file as an input for the second patch in that file, but it doesn't make a (semantic) difference, given that the target file is re-created before the first patcher is run.
• Resets the cache for the target file after each run, so that newly added records will be visible to later patchers.

Fixes #20