PLMP/C Merge and Cosmology Test

Cosmology Test

With the help of Bruno, who provided the initial conditions and parameter files (PR #383), I added a cosmology test, PR #390 and added support for checking the gravity files in the system tests.

PLMC and PLMP Merge

I merged our two PLM kernels into one with a switch to control if limiting is done in the characteristic or primitive variables. I was able to reuse some of my work from when I tried fusing the PLMC and Riemann solver kernels (PR #382) and the new version is a single unified PLM kernel that can do limiting in either set of variables. Details are in PR #391.

Other

• Responding to reviews and keeping PRs up to date, mostly PR #371