Rewritten finding random position in room.

git-svn-id: http://keeperfx.googlecode.com/svn/trunk@1419 40a56aae-0377-11df-bfb3-7781b9cb07ea
Fixed a triangle leak possibility on overflow.

git-svn-id: http://keeperfx.googlecode.com/svn/trunk@1420 40a56aae-0377-11df-bfb3-7781b9cb07ea