render.py can now export blurred image as .png

[Alexander-Zangl]

Feature Update

• The gui of the tool mask image within render was expanded upon the button Save Blur.
• Executing the button exports the current blurred image as .png file in the same directory as the loaded .hdf5 file.
• Standard naming convention of the exported file is the name of the .hdf5 file with _blur appended to it.

[rafalkowalewski1]

good job!