Developing dlib

To do a dlib release

Create a branch.
Fill in the release date in NEWS.md, and commit that.
Create an annotated vSEMVER git tag:
```
git tag --annotate --message='Release 1.2.0' v1.2.0
```
Having looked at the release notes in NEWS.md, you should have an idea of whether this needs to be a minor version bump or a patch version bump.
Push the tag and branch to GitHub:
```
git push origin v1.2.0 my-branch-name
```
Create a pull-request for the branch.

That's it!