Leak in getter function generated with CppGenerator::writeGetterFunction when `newWrapperSameObject` is true

The getter function generated with CppGenerator::writeGetterFunction when
the function local variable newWrapperSameObject is true creates a new wrapper
object on every call, resulting in memory leak

The following code demonstrates memory leak in accessing the `format` property of QtGui.QTextEdit.ExtraSelection objects.

from __future__ import print_function
import psutil, os
from PySide2 import QtWidgets, QtCore
a = QtWidgets.QApplication([])
tf = QtWidgets.QTextEdit.ExtraSelection()
mem = [0]*100
p = psutil.Process(os.getpid())
for i in range(100):
    for j in range(1000):
        tf.format
    mem[i] = p.memory_info().rss
print('memory leak per format access:', (mem[-1]-mem[0])/100.0/1000)
for i in range(100):
    for j in range(1000):
        tf.cursor
    mem[i] = p.memory_info().rss
print('memory leak per cursor access:', (mem[-1]-mem[0])/100.0/1000)

Output

memory leak per format access: 272.50688
memory leak per cursor access: 279.59296

The issue is that in the generated function `Sbk_QTextEdit_ExtraSelection_get_format` a new wrapper object is created on every access in the following line:
`PyObject* pyOut = Shiboken::Object::newObject((SbkObjectType*)SbkPySide_QtGuiTypes[SBK_QTEXTCHARFORMAT_IDX], &(cppSelf->format), false, true);`

I think a solution would be to first check if a binding for the cppField is already registered and return the binding in that case instead of creating new binding.