Update intro.rst

some initial edits
need to pass recentEvents when update button pressed
shifted maxDays check to incoming module; time sort saveEvents before adding to recentEvents
improved initial loading of recentEvents
changes to homepage text from John Baez
Merge branch 'patch-1' of https://github.com/johncarlosbaez/spnet into tmp
moved update_subscribers() to Person class; run in background thread
refactored update_subscriptions() to be more efficient, run in background on every login
implemented simple _forceReload mechanism for user display
corrected inaccurate invitation message
made Person.subscriptions into ArrayDocument class to store topics as well as author; made update_subscriptions() avoid querying Person collection