#23 Addition turned into power-of from loading files

[David Piuva]

I tried creating a data flow graph with channel 0 from an image and adding the double 128.0 to it. After saving and loading the project, the addition node had turned into a power-of node connected and located in the same way. This caused the output image to become fully white instead of bleached.

I'm using 64-bit Ubuntu 16.04 with an Intel Core i7-7700 CPU and 16 GB RAM. I installed from endrov-2.23.0.1361460421.deb.