Refactor volume calculation

[brbass]

Summary

• Volume upgrade
  • Separates the volume calculation from RKCorrections and adds controls for when the volume is updated. Previously, the Voronoi was being calculated way too often in VoronoiCells and getting overwritten by the volumes from RKCorrections.
  • Makes VoronoiCells inherit from VolumeUpdate. It optionally overwrites its own volume calculation with the user's choice of volume.
  • Lets the user choose the volume for all packages, not just RKCorrections.
  • Stores both 3D (annulus or spherical shell) volume and patch volume, which are the same in Cartesian coordinates.
• Physics package requirements upgrade
  • requireConnectivity, requireGhostConnectivity, requireOverlapConnectivity, requireIntersectionConnectivity have been replaced by requireConnectivity
    • Returns {conn, ghost, overlap, intersection}
  • requireVoronoiCells has been replaced by requireVolumes
    • Returns {explicit, implicit, voronoi}
  • requireReproducingKernels, requireReproducingKernelInFinalize, requireReproducingKernelHessian have been replaced by requireReproducingKernels
    • Returns tuple {explicit, implicit, hessian}
• Boundary fixes
  • Boundaries were not being ordered consistently.
  • Adds a priority to Boundary to codify this.
• Bugfix
  • GenerateRatioSphere accessing the wrong element when SPH = True

Timing

Most of the code in this MR is focused on upgrading the volume calculation, but the reason behind it was to fix the inefficiency of ASPH (the True version, not the "classic" version). Here is an example of the timing for a 3D ASPH problem run on 100 procs for 200 cycles before and after these changes. The basic result: ASPH is improved from being prohibitively expensive before to being a reasonable option now.

Function	Before this MR	After this MR	Explanation
Voronoi volume	416.7 (13.5x derivs)	98.6 (3.3x derivs)	Only in finalize, not duplicated in RK
Explicit total	379.3	172.9	No more Voronoi in derivatives for ASPH
Explicit derivs	30.8	30.0	Derivative evaluation stays the same

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ToDo :

• Annotate RELEASE_NOTES.md with notable changes.
• Create LLNLSpheral PR pointing at this branch. (PR#)
• LLNLSpheral PR has passed all tests.

[brbass]

Just a note that this MR depends on #475