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/Interpreter.h

@@ -53,6 +53,40 @@
 
 #include "Exception.h"
 
+/** Helper macro to obtain callable from an object
+ *
+ * @param _pyobj: PyObject pointer
+ * @param _name: the callable string name
+ * @param _var: the callable variable to be assigned
+ *
+ *  See FeaturePythonImp::init() for example usage
+ */
+#define FC_PY_GetCallable(_pyobj,_name,_var) \
+    do {\
+        _var = Py::Object();\
+        if(PyObject_HasAttrString(_pyobj, _name)) {\
+            Py::Object _obj(PyObject_GetAttrString (_pyobj, _name), true);\
+            if(_obj.isCallable())\
+                _var = _obj;\
+        }\
+    }while(0)
+
+/** Helper macro to obtain attribute from an object
+ *
+ * @param _pyobj: PyObject pointer
+ * @param _name: the attribute string name
+ * @param _var: the attribute variable to be assigned
+ *
+ *  See FeaturePythonImp::init() for example usage
+ */
+#define FC_PY_GetObject(_pyobj,_name,_var) \
+    do {\
+        _var = Py::Object();\
+        if(PyObject_HasAttrString(_pyobj, _name))\
+            _var = Py::asObject(PyObject_GetAttrString (_pyobj, _name));\
+    }while(0)
+
+
 namespace Base {
 
     using std::string;
@@ -87,6 +121,20 @@ protected:
     PyObject *_exceptionType;
 };
 
+inline Py::Object pyCall(PyObject *callable, PyObject *args=0) {
+    PyObject *result = PyObject_CallObject(callable, args);
+    if(!result)
+        Base::PyException::ThrowException();
+    return Py::asObject(result);
+}
+
+inline Py::Object pyCallWithKeywords(PyObject *callable, PyObject *args, PyObject *kwds=0) {
+    PyObject *result = PyObject_Call(callable, args, kwds);
+    if(!result)
+        Base::PyException::ThrowException();
+    return Py::asObject(result);
+}
+
 /**
  * The SystemExitException is thrown if the Python-internal PyExc_SystemExit exception
  * was thrown.