Style manual: change all link:http://...[] to drop the link: prefix.

It is not required.  Also in one case there was a double :: which was
causing a single : to show up in the output.

Colour the links in pdf output, to make them more obvious.


git-svn-id: http://svn.mkgmap.org.uk/mkgmap/trunk@3288 25d90789-57f7-4ee0-8453-03a3dfeeeb22