This lets us increase the sprite width from 14 to up to 29 bits, effectively nulling the old sprite limit. Table changes in next commit.
Only doc landscape_grid.html has been updated, landscape.html will be done latter. -CodeChange: Replace a direct access to m6 with SetTropicZone in InitializeLandscape, as it is the only part of m6 still untouched without the brute-forced m6=0