Add change log file.

[skywinder]

Hi, as I can see, you are carefully fill tags and labels for issues in your repo.

For such cases I create a github_changelog_generator, that generate change log file based on tags, issues and merged pull requests from Issue Tracker.

This PR add change log file to your repo (generated by this script).
You can check, how it is look like here: Change Log

Some essential features, that has this script:

• it exclude not-related to changelog issues (any issue, that has label question duplicate invalid wontfix )
• Distinguish issues according labels:
  • Merged pull requests (all merged pull-requests)
  • Bug fixes (by label bug in issue)
  • Enhancements (by label enhancement in issue)
  • Issues (closed issues w/o any labels)
• Generate neat Change Log file according basic change log guidelines.

You can easily update this file in future by simply run script: github_changelog_generator dagwieers/unoconv in your repo folder and it make your Change Log file up-to-date again!

Hope you find this commit as useful. 😉