Proper fix for the quat.to_axis_angle bug.

Apparently, I was getting a number so close to -1 (but just under) that
it just printed as -1. Fuck off.

modules/quat.lua

@@ -131,7 +131,7 @@ function quaternion.unit()
 end
 
 function quaternion:to_axis_angle()
-	if self.w > 1 then
+	if self.w > 1 or self.w < -1 then
 		self = self:normalize()
 	end
 
@@ -139,13 +139,6 @@ function quaternion:to_axis_angle()
 	local s     = math.sqrt(1-self.w*self.w)
 	local x, y, z
 
-	-- HACK: Why the fuck is this ever NaN?
-	-- I suspect a LuaJIT optimization bug - it doesn't happen in the repl.
-	if angle ~= angle then
-		angle = math.pi * 2
-		s     = 0
-	end
-
 	if s < constants.FLT_EPSILON then
 		x = self.x
 		y = self.y