GitHub compare helper

Adds UI to GitHub commits pages to easier create GitHub compare urls

Manually typing the GitHub compare url takes too much time. Use this simple UI add-on to do it much faster! Note: Works the same way GitHub compare urls are normally generated i.e. from the first SHA of a commit to (but not including) the last SHA of a commit. This means the generated compare url will, for branches, include the top selected commit but not the last selected commit (but the commit before). For pull requests it is the opposite. NEW! Now also works on pull requests! ----------------------------------------------------- Source: https://github.com/hengun348/GitHub-compare-helper Thanks https://github.com/acetrand and https://github.com/bradsk88 for pull request contributions!