Merge pull request #26 from eggrobin/master

Catch up with master, there are still a couple of things to add before deleting this branch.
Merge pull request #28 from eggrobin/master

Catch up with master.
Made the placeholder thinner.
Fixed text commas typeset as math up to line 202. Also found an x which should have been typeset as a vector.
Fixed more commas and full stops, fixed the layout here and there, added some of the `red man's'' remarks.
Merge pull request #29 from eggrobin/fix-fonts

Catch up.
Fixed operator spacing; introduced \\op[letter] commands for operators.
Merge pull request #30 from eggrobin/lecture-2013-03-16

Lecture 2013 03 16
Fixed typos in font test file.
Match math font and text font sizes.
Merge pull request #31 from eggrobin/fix-fonts

Fix fonts