Change rgl.* functions to *3d

[dmurdoch]

Some upcoming changes to the rgl package will require changes to inlabru.
I will be deprecating a number of rgl.* function calls. You can read
about the issues here:

https://dmurdoch.github.io/rgl/articles/deprecation.html

I have made the required changes in the attached PR.

Other changes are also required to pass checks, as the code in the globe() function gives this error:

fm_sp_get_crs() was deprecated in inlabru 2.7.1 and
is now defunct.

I have not made that change.

[finnlindgren]

Thanks! I'd forgotten I hadn't made all the internal fixes for fm_sp_get_crs --> fm_CRS; it was meant to be only a depcrecated_warn().

[finnlindgren]

Now on CRAN due to #193