Add basic reader that computes points.

Add cellsets.

Add surface index cell var.

Read multiple surfaces.

Put num_theta and num_zeta in the json.

Move cellset construction into CellSet.cxx

bug fix. Had the zeta/theta swapped.

Handle the duplicate points stuff.

Use cleangrid filter to cleanup data.

Fix the support for multiple surfaces.

Add option to specify the surfaces to extract.

code cleanup.

Add surface_index variable

Worklet-ize the cell set creation.

Cleanup CellSetGX::PostRead

Undo debug statement in json code.

Add validators to test, fix bug in cellset.

Code cleanup....

Code cleanup.

more code cleanup.

Code cleanup.

Code cleanup...

Fix compiler warnings.

fix compile warnings.

Add filename to test.

code cleanup.