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/Rotation.h

@@ -84,8 +84,10 @@ public:
     void operator = (const Rotation&);
 
     void multVec(const Vector3d & src, Vector3d & dst) const;
+    Vector3d multVec(const Vector3d & src) const;
     void scaleAngle(const double scaleFactor);
     bool isSame(const Rotation&) const;
+    bool isSame(const Rotation&, double tol) const;
     //@}
 
     /** Specialty constructors */