VEC: Fix the inRange function

It now takes a PROPER square, as in ((xmin, ymin), (xmax, ymax))
instead of ((xmin, xmax), (ymin, ymax)) and also works
with negative values.

Because the meaning of the arguments has changed, we also
had to fix all uses of it.

GUI/Gtk.hs

@@ -2,6 +2,7 @@
 
 module GUI.Gtk (makeGUI) where
 
+import Algebra.Vector (dimToSquare)
 import Control.Applicative
 import Control.Monad(unless)
 import Control.Monad.IO.Class
@@ -308,8 +309,9 @@ saveAndDrawDiag fp fps mygui =
                 haveGrid      = gridActive,
                 showCoordText = coordTextActive,
                 quadPath      = quadPathEntry',
-                rangeSquare   = (fromMaybe (0, 500) rxDim,
-                                 fromMaybe (0, 500) ryDim)
+                rangeSquare   = case (rxDim, ryDim) of
+                  (Just xd', Just yd') -> dimToSquare xd' yd'
+                  _                    -> ((0, 0), (500, 500))
                 })
               mesh)
         (s, r)  = renderDiag daW daH diagS