Feedback Energy Injection Changes

This MR includes:

• A limiter for the diffusion in ANARCHY-DU that enables feedback in EAGLE to work
• Minor fixes to some hydro test scripts that were broken that I came across
• Adds a script to the FeedbackEnergy_3D test to plot energy as a function of alpha_diff.

examples/Cooling/FeedbackEvent_3D/.gitignore

+nocool_*/*
+default_*/*