Replace rgl.* functions with *3d

[dmurdoch]

An upcoming release of rgl will deprecate a large number of rgl.* functions, including some used in tsDyn. This PR replaces them with equivalents. It will work both before and after the change. For details on the deprecation, see

https://github.com/dmurdoch/rgl/blob/deprecated/vignettes/deprecation.Rmd

[MatthieuStigler]

Thanks a lot for letting us know and for even making a pull request, much appreciated!!

[MatthieuStigler]

@dmurdoch when is the new release expected to come on CRAN? Thanks!

[dmurdoch]

I plan to submit it in a week or so.

[MatthieuStigler]

ok, thanks!