Maps get a clean background again.

FIXED
• The map background had been showing a watermark across it ever since its
  supplier closed free access. It gives way to clean light and dark backgrounds,
  served by OpenFreeMap from OpenStreetMap data
• Place names are now drawn on the fly: they stay sharp at every zoom level and
  no longer appear twice, in two alphabets
• Maps exported to PDF, Word and PowerPoint carry the new background too
• Slides are no longer cut off at the sides when presenting from an iPhone held
  upright