Thermalized LB: test 4 rel time model velocity and pressure fluctuations

This changes the fluctuating LB test to match as closely as possible what we are going to use. Model with 4 relaxation times for shear/bulk/odd/even modes. Tests:

• mass conservation
• momentum conservation
• <m v^2> = k_B T
• Maxwell velocity distribution
• average stress tensor
• stress tensor fluctuations accodring to Duenweg, Schiller, Ladd