Merge pull request #98 from eggrobin/lecture-2013-04-25

Lecture 2013 04 25
Merge pull request #99 from eggrobin/lecture-2013-04-25

Almost done. The prospect of having a backlog when I'm the only one able...
Merge pull request #100 from eggrobin/lecture-2013-04-30

Lecture 2013 04 30
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Merge pull request #101 from eggrobin/fix-hboxes

...
To a Skylark.
Merge pull request #102 from eggrobin/more-poetry

To a Skylark.
Merge pull request #103 from eggrobin/master

Catchup.
A complex thing that you can't visualise.
Merge pull request #104 from eggrobin/lecture-2013-04-25

Lecture 2013 04 25
Merge pull request #105 from eggrobin/master

Catchup.