Load SIF layout automatically if it exists

[ozgunbabur]

When we visualize existing results, the webserver shows the directory of ".sif" files on the left. If there is a corresponding ".format" file, we don't see them but they are used during loading the graph.

Another possible file type for SIF graphs is the ".layout" file. If it exists, then the load operation should set the layout using the locations in this file. Currently, users can load layouts through "File --> Import --> SIF Layout".

We want the same operation to execute automatically during SIF loading if there is a ".layout" file with the same name.