Base: misc patches

Convenience macros/function (in Interpreter.h)

* FC_PY_GetObject/Callable(), look for callables in a python object,
  which will be used in future patch to improve performance in various
  python observer/features.

* pyCall(WithKeywords)(), helper function to invoke the callable

Matrix4D:

* hasScale(), check if there is any scale in the transformation. If so,
  further check if the scale is uniform or not. This will be used in
  future patch for Part::TopoShape to decide which type of transform to
  apply.

Placement:

* translate/rotate(), new convenience API

Rotation:

* isSame/multiVec(), new convenience API

Polygon2d:

* Intersect(), GetCenter(), new convenience API.

FlagToggler:

* New class for exception safe flag toggling, similar to StateLocker
  but with template (actually, FlagToggler is added earlier by me).

BitsetLocker:

* New class for exception manipulation of a std::bitset variable.

src/Base/Tools2D.h

@@ -89,7 +89,7 @@ public:
   inline BoundBox2d (double fX1, double fY1, double fX2, double fY2);
   inline bool IsValid (void);
   inline bool IsEqual(const BoundBox2d&, double tolerance) const;
-  
+
   // operators
   inline BoundBox2d& operator= (const BoundBox2d& rclBB);
   inline bool operator== (const BoundBox2d& rclBB) const;
@@ -102,6 +102,11 @@ public:
 
   // misc
   bool Contains (const Vector2d &rclV) const;
+
+  inline Vector2d GetCenter() const {
+      return Vector2d((MinX+MaxX)/2,(MinY+MaxY)/2);
+  }
+  
 };
 
 /** Line2d ********************************************/
@@ -160,6 +165,7 @@ public:
   BoundBox2d CalcBoundBox (void) const;
   bool Contains (const Vector2d &rclV) const;
   void Intersect (const Polygon2d &rclPolygon, std::list<Polygon2d> &rclResultPolygonList) const;
+  bool Intersect (const Polygon2d &rclPolygon) const;
   bool Intersect (const Vector2d &rclV, double eps) const;
 
 private:
@@ -308,7 +314,6 @@ inline Vector2d& Polygon2d::At (size_t ulNdx) const
   return (Vector2d&) _aclVct[ulNdx];
 }
 
-
 inline Line2d::Line2d (const Line2d &rclLine)
     : clV1 (rclLine.clV1),
       clV2 (rclLine.clV2)