Flowfields

[brean]

Implement flowfields, inspired by https://www.youtube.com/watch?v=QCsh_nzF0FY

[brean]

For visualizing the flow fields we can use UTF-8 arrows:

    arrow_map = {
        (0, 0): '·',   # Target
        (1, 0): '→',   # Right
        (-1, 0): '←',  # Left
        (0, 1): '↓',   # Down
        (0, -1): '↑',  # Up
        (1, 1): '↘',   # Down-Right
        (-1, 1): '↙',  # Down-Left
        (1, -1): '↗',   # Up-Right
        (-1, -1): '↖'  # Up-Left
    }