Enhancement: Copy new config options from default.ini if not present in config.ini

[bdbenim]

Since configupdater is used to handle the config files instead of the builtin configparser, changes can be made to the config programmatically without deleting comments or otherwise changing formatting in a way the user would not expect. This means that if new config options are added in the future to default.ini, such as in #14, then these new default values can automatically be added to the user's config. This should be accompanied by a log message notifying them of the new option so that they can configure it.

This relates to #17 but doesn't entirely resolve it.