CylindricalManifold implementation

I adapted this from the old Manifold branch. 

Here is how it looks:

![screen shot 2014-08-06 at 14 53 07](https://cloud.githubusercontent.com/assets/2919756/3827061/8c01c130-1d69-11e4-9345-d61d218bd522.png)

At least, tolerance is a value that can be chosen upon construction of a manifold.

An alternative would be to use std::numeric_limits<..>::epsilon(), but this would require to have a notion of typical length scale...