The config file organisation previously used hard-coded Python values dumped to a file
inside the Finesse source directory then copied to the user's config directory. This
would present a problem when Finesse is installed as a package in a non-writable
directory. Furthermore, the first step of dumping Python data structures to the
config file was unnecessary - the config file could instead be provided as-is in the
source tree, and copied on load to the user's config directory. This avoids the need
for write permissions on the Finesse source directory, and has the added advantage of
us being able to include comments in the configuration example files to guide the user.

The code now copies the "finesse.ini.dist" and "usr.ini.dist" files from the finesse
package into the user's config directory on load, the latter only if it doesn't already
exist. These files are included in the setup.py package resources list so should get
bundled as part of sdists and bdists, and these are loaded via Python 3.7's new
importlib.resources module to avoid having to load the heavier pkg_resources library.

Finally, the CLI now includes support for listing the current parsed configuration,
listing the files which were used to make it, allowing the user to open their user
configuration in the default system editor, and allowing them to reset their user
configuration with the default.