Visual mode, auto align textures: actually, it won't break anything if we...

Visual mode, auto align textures: actually, it won't break anything if we vertical clamp texture offsets of a 3d floor sidedef while auto-aligning (this reverts a part of previous commit)...
Classic modes: event lines are drawn once again while panning the view (I've disabled this a while ago trying to fix performance problems in Classic modes).