Working UI for setting & saving OTU mapping hints 

We can now set a search context and a series of (regex-powered) substitutions to streamline name mapping in the TNRS. Changes to these are visible in the on-screen 'Modified labels'. All these hints are now saved in the Nexson and available for use by outside mapping tools.

Also includes a fix for failed Github logins (affects old GH user profiles with no full name).