The intention here is to have the config file content and parser
be derivied from the command line types and flags. Now instead
of having a saved config type that contains additional
information to that kept in command line parameters we now put
all the information in the command line settings type and make
the saved config just the aggregation of the settings for
various key commands like configure, install, upload. There's
also an extended GlobalFlags type with the things like repos,
cache dir etc. When we generate the initial config file we put
in commented out versions of all (non-deprecated) valid fields,
along with their default values. The aim is to make the config
file self-documenting.