[CLI-UPDATE] v2.13 with improved image caching

[oscarlevin]

A new version of the PreTeXt-CLI (v2.13) is now available on the Python Package Index at https://pypi.org/project/pretext/.  It includes a large number of small improvements to themes and other updates from core pretext, as well as a new method for caching some in-source assets.

In particular, if your source has latex-image, asymptote, or sageplot assets, when you build with the CLI (`pretext build`), you will notice a new folder in your project folder named .cache.  This will contain copies of the images produced from those source elements with long strings of apparently random characters for their names.  The advantage of this is that the next time you build, if the source of an asset has not changed, the CLI will know to just copy the correct image to the correct place (with the correct name) instead of running the external program to create the image again.  This should be much more efficient than running the generation script for each individual image that has changed.  Let us know how this is working for you.

We recommend that you include the .cache folder in your .gitignore file if you manage your project with git.

Upgrading instructions

You can upgrade from any release with:

pip install pretext --upgrade

(or perhaps `python3 -m pip install pretext --upgrade` or `pipx upgrade pretext` depending on your system).  

If you currently have pretext v2.11 or greater, you can upgrade with `pretext upgrade`.

Please reach out via https://groups.google.com/g/pretext-support for help, or report issues at https://groups.google.com/g/pretext-dev to improve future releases of the CLI.

On behalf of the PreTeXt team,

Oscar.