Allow CTK PythonQt python module to be imported outside of a Qt appli…

…catio,

On Linux, I was able to import the ctk module doing the following:

$ cd /path/to/CTK-build/CTK-build/bin
$ PYTHONPATH=./Python/ python
>> import ctk
>> import pprint as pp
>> pp.pprint(dir(ctk))
['QAbstractButton',
 'QAbstractItemModel',
 [...]
 '__builtins__',
 '__doc__',
 '__file__',
 '__name__',
 '__package__',
 '__path__',
 'ctkActionsWidget',
 'ctkAddRemoveComboBox',
 'ctkAxesWidget',
 'ctkBasePopupWidget',
 'ctkButtonGroup',
 'ctkCallback',
 'ctkCheckBox',
 'ctkCheckBoxPixmaps',
 'ctkCheckableComboBox',
 'ctkCheckablePushButton',
 'ctkCollapsibleButton',
 'ctkCollapsibleGroupBox',
 'ctkColorDialog',
 'ctkColorPickerButton',
 'ctkComboBox',
 'ctkCommandLineParser',
 'ctkCompleter',
 'ctkConsole',
  [...]

CMake/ctkMacroWrapPythonQtModuleInit.cpp.in

@@ -3,6 +3,8 @@
 #include <PythonQt.h>
 #include <Python.h>
 
+#include <QCoreApplication>
+
 //-----------------------------------------------------------------------------
 static PyMethodDef Py@TARGET_CONFIG@PythonQt_ClassMethods[] = {
 {NULL, NULL, 0, NULL}};
@@ -52,6 +54,12 @@ void copyAttributes(PyObject* orig_module, PyObject* dest_module)
 //-----------------------------------------------------------------------------
 void init@TARGET_CONFIG@PythonQt()
 {
+
+  if (!QCoreApplication::instance())
+    {
+    PythonQt::init(PythonQt::PythonAlreadyInitialized);
+    }
+
   static const char modulename[] = "@TARGET_CONFIG@PythonQt";
   PyObject *m;