Avoid integer-division in the script making ICs for the square test.

examples/HydroTests/SquareTest_2D/makeIC.py

@@ -25,8 +25,8 @@ from numpy import *
 # Parameters
 L = 64            # Number of particles on the side 
 gamma = 5./3.     # Gas adiabatic index
-rho0 = 4          # Gas central density
-rho1 = 1          # Gas outskirt density
+rho0 = 4.0        # Gas central density
+rho1 = 1.0        # Gas outskirt density
 P0 = 2.5          # Gas central pressure
 P1 = 2.5          # Gas central pressure
 vx = 0.0        # Random velocity for all particles