ENMeval update

[jamiemkass]

ENMeval has the buildRMM() function, which makes an RMMS metadata object for the ENMeval output. It was not TRUE before because it was not a "main feature", but as the package automatically runs this function and offers the metadata output with the tuning results, I decided it would be appropriate to turn on "metadata" in the package characteristics.

I also made some plotting changes for the figures in the file "ms_figs.R".