fluxnet 0.3.0

• Adds a new function, flux_install_shuttle() which accepts the name of a virtualenv to use and a version of fluxnet-shuttle to install. It pulls these from envvars, by default, making it easy to configure via a project-level .Renviron file. It can be run as a separate step, but this is optional as it will be called automatically the first time flux_listall() or flux_download() are run.
• flux_download() no longer shows a progress bar as it downloads files.
• Optionally, you can provide a list containing your Ameriflux user name, email, and intended use to flux_download() via the new user_info argument and flux_amf_credentials() helper function.
• To get all available sites with flux_download(), use site_ids = NULL. site_ids = "all" is deprecated.
• flux_download() now uses the fluxnet_shuttle Python library rather than httr2 to perform downloads.
• Fixed a bug in flux_badm() that would cause it to error when some "BIF" files contained additional optional columns (#57)
• The use_cache argument of flux_listall() has been removed.
• flux_listall() gained a clean_cache argument to set the number of recent snapshot CSVs to keep. Defaults to 10.