Bug

In agent portrayal, the marker is supposed to be able to take on all matplotlib marker types. But the tuple way of defining markers is currently not compatible in MESA. This issue can be replicated by replacing the marker in any one of the examples (here I have taken boid_flockers) with say (3, 0, 30). This is supposed to convert the agents to a 3 sided polygon tilted by 30 degrees, if we replaced 3 with 4 we will get a square instead.
The main reason for the error was that during agent data collection, numpy was turning the tuples into arrays. I have fixed the issue in this PR.

I just ran boid_flockers using tuples in the following code after the fix:

def boid_draw(agent):
    neighbors = len(agent.neighbors)

    if neighbors <= 1:
        return {"color": "red", "size": 20, "marker": "o"}
    elif neighbors >= 2:
        return {"color": "green", "size": 20, "marker": (3, 0, 60)}

I am not exactly sure, but I was wondering if merging this fix will help us later implement a solution to #1150, I can try working on that for boid_draw if it is feasible...