Preparing a CRAN submission

Checks

git branch v4.6 v4.5
git rebase master v4.6
git commit --amend --date=now --no-edit
git push github v4.6

Use the webform for submission.
Example submission note text:
The package has been checked under R-4.1.0, R-release, and R-devel on linux, osx, and windows. I have checked for memory leaks using 'valgrind'. There are two new NOTEs generated, concerning S3 generic/method consistency. These are false positives, since the functions in question filter.mean and filter.traj are themselves S4 generics. I have checked that the S3 method dispatch system works properly. In any case, these functions have been deprecated as of this version in favor of functions named filter_mean and filter_traj, so this false positive will go away when these functions are removed in a future release. I have verified that this release does not break the reverse dependencies listed on CRAN, with the exception of spatPomp. I am one of the developers of that package and we have prepared a CRAN release of this package that corrects this problem. We will submit this as soon as this version of pomp is published to CRAN.