Create spline lines/polygons

[zsiki]

Finishing the spline on a memory layer (CADLayer Lines) by right button click I got the following error:
An error has occured while executing Python code:
Traceback (most recent call last):
File "/home/siki/.qgis2/python/plugins/cadtools/tools/spline.py", line 96, in canvasPressEvent
self.createFeature()
File "/home/siki/.qgis2/python/plugins/cadtools/tools/spline.py", line 148, in createFeature
if dlg.exec_():
AttributeError: 'NoneType' object has no attribute 'exec_'

The condition should be changed to
if dlg is not None and dlg.exec_():
or do not activate tool if memory layer is editable