jp (blog, common): various fixes in common and blog: - parse_args has been moved to common - cat_dir is converted to str on BaseEdit init, so it can be use to make str path for files manipulation - fixed use of EDITOR_ARGS_MAGIC when use_metadata is False - fixed unlink of metadata files when use_metadata is False

Use this module to temporary store files that need to be integrated to other
projects such as Wokkel.

For example, the changeset that introduced this folder adds RSM (XEP-0059)
support to Wokkel. The files in sat.tmp.wokkel are imported over the initial
wokkel files from sat.plugins.__init__.py