Added the ability to specify multiple crop zones.

docs/config.rst

@@ -709,8 +709,8 @@ values. The valid configuration keys are listed below.
 .. _crop:
 
 ``crop``
-    You can use this to render a small subset of your map, instead of the entire
-    thing. The format is (min x, min z, max x, max z).
+    You can use this to render one or more small subsets of your map, instead
+    of the entire thing. The format is [(min x, min z, max x, max z)].
 
     The coordinates are block coordinates. The same you get with the debug menu
     in-game and the coordinates shown when you view a map.
@@ -723,6 +723,14 @@ values. The valid configuration keys are listed below.
                 'crop': (-500, -500, 500, 500),
         }
 
+    Example that renders two 500 by 500 squares of land:
+
+        renders['myrender'] = {
+                'world': 'myworld',
+                'title': "Multi cropped Example",
+                'crop': [(-500, -500, 0, 0), (0, 0, 500, 500)]
+        }
+
     This option performs a similar function to the old ``--regionlist`` option
     (which no longer exists). It is useful for example if someone has wandered
     really far off and made your map too large. You can set the crop for the