Performance tests improvements

[michal367]

List of changes:

• added FRED and PyMedPhys performance tests written in Python.
• added setup.sh script for project setup on Linux.
• improve plot script (plot_gamma_times.py): added possibility to plot more than two csv files, significantly improved plot appearance, added possibility to save plot to file.
• refactored gammaPerf.cpp.
• better use of tolerance in Interpolation.cpp. Thanks to this it has lower value.
• allowed evaluated img to have more frames than reference img in classic 2.5D.
• other small changes.