Allow square element to be a rectangle

src/tools.py

@@ -1,3 +1,5 @@
+import math
+
 # sign function
 def sgn(x):
     if x>=0:
@@ -20,3 +22,10 @@ def remove_fromlist(a,x):
         a[a.index(x)]=a[len(a)-1]
         a=a[:len(a)-1]
     return a
+
+# snap to a grid: ceiling
+def ceil_grid(x,size):
+    return math.ceil(x/size)*size
+# snap to a grid: floor
+def floor_grid(x,size):
+    return math.floor(x/size)*size