Add 3D tutorial

[lcarasik]

All current tutorials are 2D and it would be useful for new users doing 3D domains to have a tutorial to work from.

A few ideas for this:

1. Genbox created 2-D cross-section for a square or rectangular box that is extruded using n2to3
2. Genbox created 2-D cross-section for a circle or annulus that is extruded using n2to3

Either 1 or 2 shown to work with a velocity inlet ('v ') and pressure outlet ('O ') and/or periodic in the streamwise direction using "P " with a volumetric flow

This way it's possible to show of geometry creation in 3-D as well as how to apply to boundary conditions for periodic and non-periodic domains.

[lcarasik]

We're currently working on developing this for basic pipe flow including heating, it could be done using laminar flow as a starting point.

[lcarasik]

It should include usage of history points with temperature as a passive scalar.

i.e.
Number of points
Point coordinates
Time, Ux, Uy, Uz, P, T