Fix gravity/warp lines being modified during draw

While warp lines were being drawn, they also got resized to
automatically fit between collision. In renderfixed, gravity lines are
resized the same way. Doing logic while drawing is very poor practice,
so resizing of these has been moved into logic, and merged together.

Aside from some more cleanup, this commit also removes the very poorly
done right click emulation, when you hold CTRL and click. It never
worked well in the past, and even requires a right click to use, so
there's not really any point to keeping it around.