Added cylinder model;

Documentation;
Added a cylinder that renders like a box just to test that it's working;
Added utility class Vertex;

Begin to create the generateGeometry method for cylinder;
Added Face class to keep vertices;

Improvements on the generateGeometry method;
Refactored;
Cylinder almost done, missing the caps!
Cylinder done;
Added support to define the number of sides in the model;

The cylinder also support a variable number of sides which are calculated at runtime;
Merge branch 'cylinder-support' into Silver