hasktags.cabal: update source-repository to MarcWeber/hasktags
hasktags.cabal: do not duplicate version constraints for tests
hasktags.cabal: wider dependency range for platform 2013.2
Implement "ignore symlink directories" by default similar to what
liyang suggested in pull request #1.
Use -L if you need old behaviour

Also allow passing list of files to STDIN. Example:
  find . --name "*.hs" | hasktags STDIN

Add an option to specify hs suffixes. "" will mean "all files".
If you have need for this option consider contributing a patch changing
the defaults
fix Readme