Add the 0.7.1 version info to the changelog on master

[lardieri]

Important: Please do not squash or rebase!

I've set this up as a merge commit, specifically so it accomplishes two desirable goals:

• Add the 0.7.1 version info to the changelog on master.
• Additionally, close out the v0.7 branch by joining it back into master, so we don't carry around an appendix branch forever.

If you want to see what this looks like, you should clone my fork and use a graphical visualizer ("subway map") to look at the branch structure.

Please let me know if you have any questions.

[lardieri]

Also, just to be explicit: I'm choosing this approach to avoid rebasing master — which, as you pointed out, is not regarded as good practice.

I understand that merge commits are generally not used in this repo (I can see that they're turned off in the Settings), but in this case, I believe it's the approach that makes the most sense and causes the least disruption.