an incremental step toward better converters

this is a step toward a better converter system for configman.  The immediate benefit to this change is that the excessive quoting done by the ini handler is gone and paths to classes are completely qualified.

Some redundancy has been eliminated (there was more than one timedelta converter), and the converter section has been arranged into three sections: utility, from string and to string


there are a lot of these old name to new name mappings and I don't want to generate a lot of noise on stderr.  For now, I'd just like to leave these as alternative names.  If we feel the need, we can deprecate at a later time.