1. We have DTDs but no sample XML for the following SportInfo types,
   which have therefore been left unimplmented for now:

   * CBASK_StealsXML.dtd

2. The following DTD types were handled (in some form) by the old
   FeedGrabber. They are not yet handled by htsn-import (some may not
   be valid):

   * AutoRacingGridXML
   * CBASK_Individual_Stats_XML
   * Cbask_Roster_XML
   * cbaskteamschedulexml
   * CBATeamScheduleXML
   * CFLTeamScheduleXML
   * CFLTotalTeamScheduleXML
   * Minor_Baseball_TeamScheduleXML
   * MinorLeagueHockeyTeamScheduleXML
   * MLB_Boxscore_XML
   * MLB_IndividualStats_XML
   * MLB_Probable_Pitchers_XML
   * MLB_Roster_XML
   * mlbteamschedulexml
   * mlsteamschedulexml
   * NBA_Boxscore_XML
   * NBA_Individual_Stats_XML
   * NBA_Roster_XML
   * nbateamschedulexml
   * NCAA_Basketball_Boxscore_XML
   * NCAA_FB_TeamScheduleXML
   * NCAAHockeyTeamScheduleXML
   * NFL_Boxscore_XML
   * NFL_CompBox_XML
   * nfldepthchartxml
   * nflteamschedulexml
   * nhlteamschedulexml
   * WCBaskTeamScheduleXML
   * WNBA_Boxscore_XML
   * WNBA_Individual_Stats_XML
   * WNBATeamScheduleXML

3. Consolidate all of the make_game_time functions which take a
   date/time and produce a combined time.

4. Factor out test code where possible; a lot of them differ only in
   the filename.

5. Combine test XML files where possible. We don't need to e.g. import
   two copies of newsxml just because one has an empty attribute that
   we want to test: we could just delete an attribute from the first
   file.