Higher auto-refinement limits

[tzanio]

This is meant to address the issue where small meshes are curved but refined versions of them appear to lose the curvature in GLVis. See also this task in https://github.com/GLVis/glvis/pull/284

Command-line option to ensure minimal level of refinement to large meshes don't show as linear by default (ping: @dylan-copeland, @psocratis)?

The reasons for that behavior are the auto-refinement limits, which previously were:

• at most 16 refinement levels (auto_ref_max = 16)
• at most 20K "refined" elements to be visualized (auto_ref_max_surf_elem = 20000)

Both of these variables are set in lib/vsdata.cpp

After considering several options, I suggest that we just increase those variables to 32 and 5M respectively.

These limits seems to work fine on modern hardware and the waiting time for large meshes is a few seconds on my Mac.

@psocratis and @dylan-copeland -- do you mind trying this on your use cases and reporting if it works well?