Finish rect2

More tests for rect-rect intersection would be good. Found a bug with
polygon from_regular. Added regression test and fixed it.

* pygorithm/geometry/polygon2.py - Fix a bug (math error, see doc changes)
* pygorithm/geometry/rect2.py - Implement all the things
* tests/test_geometry.py - test all the things for rect2

Author: Tjstretchalot

pygorithm/geometry/polygon2.py

@@ -205,9 +205,9 @@ def from_regular(cls, sides, length, start_rads = None, start_degs = None, cente
         
         Finally, each vertex is found using ``<radius * cos(angle), radius * sin(angle)>``
         
-        If the center is not specified, the bounding box of the polygon is calculated while the vertices
-        are being found, and the center of the bounding box is set to the center of the circle. This
-        is never greater than (circumradius, circumradius).
+        If the center is not specified, the minimum of the bounding box of the 
+        polygon is calculated while the vertices are being found, and the inverse
+        of that value is offset to the rest of the points in the polygon. 
         
         :param sides: the number of sides in the polygon
         :type sides: :class:`numbers.Number`
@@ -251,8 +251,6 @@ def from_regular(cls, sides, length, start_rads = None, start_degs = None, cente
         pts = []
         _minx = 0
         _miny = 0
-        _maxx = 0
-        _maxy = 0
         for i in range(sides):
             x = center.x + math.cos(angle) * radius
             y = center.y + math.sin(angle) * radius
@@ -262,13 +260,11 @@ def from_regular(cls, sides, length, start_rads = None, start_degs = None, cente
             if _recenter:
                 _minx = min(_minx, x)
                 _miny = min(_miny, y)
-                _maxx = max(_maxx, x)
-                _maxy = max(_maxy, y)
 
         if _recenter:
-            _newcenter = vector2.Vector2((_maxx - _minx) / 2, (_maxy - _miny) / 2)
+            _offset = vector2.Vector2(-_minx, -_miny)
             for i in range(sides):
-                pts[i] += _newcenter
+                pts[i] += _offset
 
         return cls(pts, suppress_errors = True)
 
@@ -520,7 +516,7 @@ def _create_link(pts):
         :type pts: list of :class:`pygorithm.geometry.vector2.Vector2`
         """
 
-        param0 = "+".join(('%28{}%2C+{}%29'.format(v.x, v.y)) for v in pts)
+        param0 = "+".join(('%28{}%2C+{}%29'.format(round(v.x, 3), round(v.y, 3))) for v in pts)
         xmin = pts[0].x
         xmax = xmin
         ymin = pts[1].y