Rearrange the licensing module

[LourensVeen]

In #96 I described a few desired changes to the licensing module, which I've implemented here. The main idea is to build more on my own experience helping engineers at NLeSC with licensing questions, because it's likely to be a good predictor of the kinds of questions the learners will get.

So the story is now arranged around the different kinds of questions they're likely to get, about 1) using software from the Internet, 2) sharing software, and 3) contributing to Open Source projects. This latter section is new. Software policies have a bit less weight, because they mostly don't yet exist.

The different parts are now:

1. Slides (updated to reflect the rest of the changes)
2. Copyright intro (as it was)
3. Exercise: finding the license (new, replaces the "licenses in use" exercise which didn't work that well)
4. Licenses (different kinds, was part 6, unchanged)
5. How to share software (new text for self-study)
6. Exercise: choose a license (as it was, previously 7)
7. University policies (was 3, unchanged, didn't want to remove it completely either)

There's no self-study text about contributing to other software, only some slides with notes. Perhaps there should be a text version as well?

Closes #96

[LourensVeen]

And I've made things look a bit prettier with the help of some awful CSS hackery, and I've moved the now-pretty license types slide because it seems to make more sense this way.

I'm ready for this to be merged.

[LourensVeen]

Ah, sorry Robin, overlooked your comment. Good idea! I'll add that in, hold on.

[LourensVeen]

Okay, added to the speaker's notes because it's probably best just mentioned there.