Bugfix of3 d primitives resolutions

Fixes #2941. And is in response to https://github.com/openframeworks/openFrameworks/pull/3093#issuecomment-49841874.

Recalculated the vertex and index strides for of3DPrimitives so the setColor and getMesh functions for ofConePrimitive, ofBoxPrimitive and ofCylinderPrimitive work as expected.


is the parens around `resZ` an oversight/error (missing +1 or so), because right now it doesn't do anything. same a bit further down.