Update and rename activematter.py to activematter2.py

[quantumtechniker]

The simulation code has been encapsulated within a function called simulate_vicsek. This makes the code more modular and easier to reuse in different contexts.

Variable and function names have been made consistent by following PEP 8 style guidelines. Variable names use underscores for improved readability.

NumPy is used for array operations wherever possible. This improves code efficiency and readability. Redundant calculations for mean_theta and trigonometric operations have been eliminated, resulting in cleaner and more efficient code.

Function parameters have been assigned default values, making it easier to run the simulation with different sets of parameters.

The plot_real_time parameter has been introduced to control whether real-time plotting is enabled. This allows flexibility in visualization.