Adding script to generate cython dependency graph
Using export mechanism to find sopt
Changing output library name
Adds virtualenv for build tree

Creates a virtualenv in the build tree.
Checks that all necessary python packages are present, and installs them.
pip_install uses pip to get location and version
Add scipy and numpy to pip_install dependencies
Added Sopt as external package

* Add scripts to add Sopt as an external project if it cannot be found.
* Remove FindSopt.cmake since Sopt now installs itself via an export mechanism.
* Inclusion of directories and targets is a bit more hand-made, since we have to include libraries
  that may not yet exist.
Add explicit dependency on looked-up packages

Also documents lookup_package.
Add CFitsIO lookup recipe

Goes some ways towards #9. It now only needs to be added (and to compile).
Changes default branch for Sopt

Adds some more docs into lookup recipes.
Wrong capitalization
Adds utilities (mkdir, ln)
lookup_package is a macro and can't use return
Add pandas to python dependencies

Adds some comments to dependencies.cmake as well.
Change virtualenv dependency

Still installing virtualenv during configure.
However, if it is not sufficiently modern, then a new version is installed from source (rather than
from pip). This ensures that pip is present.
Simplifies python dependencies.

It is difficult to get a fully functional dependency installation method for python. Too many Yaks,
chicken and eggs. So currently, we choose carefully only include those packages that are needed for
the current build (with/without testing, etc), and to fail with explicit messages.
Unsetting CFitsIO variables during lookup

This avoids cmake complaining about undefined variables.
Moved some cmake stuff to the cook-off

See issue #5.
Moves PythonPackage and PythonVirtualEnv.
These two packages are used in BEM++ as well (bempp/bempp#71).
Find a coherent python install from cookoff recipe

Goes towards issue #5. The CoherentPython package makes sure (tries to) that the python executable
and the python libraries are the same. This is also used in bempp/bempp#71.
Updating to latest GreatCMakeCookOff