initial commit
cleanup to prepare to publish

- Simplify by using a required command-line parameter as the filename.
  This is more Unix-y anyway, which is really what this tool is going
  for.
- Properly delete the temporary folder we create when the program exits.
- Add a couple of comments.
- Allow comments and newlines.
- Catch a couple of possible errors.
- Allow comments and blank lines in mindex files.

This should not have all been one commit...
README updates
add vim "plugin" (hardly deserves the name)
more documentation; example file; add LICENSE
Merge branch 'master' of https://github.com/sobjornstad/mindex

accidentally added license on two sides