Start Python Generators lab

This lab is designed to introduce Python generators.
adding content to generator labs

Added more content for combinations and permutations.  Solutions for
same added as well.
Merge branch 'master' into python
Bugfix in Bezier curve lab
Merge pull request #70 from insertinterestingnamehere/splines

Bugfix in Bezier curve lab
make Vol2 compile again
Merge pull request #71 from ayr0/fixes

make Vol2 compile again
Started the Cython lab.
Wrote most of the Cython lab.
rough draft of Cython lab
Merge branch 'master' into python
A closing note for the Cython lab
Finished Cython lab, added solutions.
Fixed a typo in the cython lab.
A major revision of the Cython lab. I corrected the motivation for the
typed memoryviews.
Further clarification of the cython lab, also added some useful notes to the solutions.
More sleight revision of the cython lab.
Added a reference to the compilation instructions in the Cython
documentation to the Cython lab.
Sleight typo fix and an update to the solutions for the cython and
linesweep labs.
Some more minor typo fixes in the Cython lab.