Guess what major breaking-news bug I just fixed B)

...

(It's that infamous intangible West/South linedefs bug, which was really a blockmap-related bug all along. AND IT WAS SO SIMPLE TO FIX!)

git-svn-id: https://code.orospakr.ca/svn/srb2/trunk@9048 6de4a73c-47e2-0310-b8c1-93d6ecd3f8cd