fix OutOfMemoryError caused by special case:
A very long line going from 65.866041/180.0 to
66.640599/180.0 . The makeBetweenPoint() routine
calculated a point with longitude -180 instead of 180.


git-svn-id: http://svn.mkgmap.org.uk/mkgmap/trunk@3350 25d90789-57f7-4ee0-8453-03a3dfeeeb22