Create agent wealth heatmap of parameter sweep

[divilian]

As discussed in 6/12 Zoom call, have param_sweep.jl create a heatmap which shows:

• Agent wealth (binned) on x-axis
• Swept parameter (e.g., ER λ) on y-axis
• Number of agents with wealth in that bin on "z-axis" (color).

[divilian]

With the new code, I'm getting ERROR: LoadError: ArgumentError: New columns must have the same length as old columns

When my machine reaches line 134 of param_sweep.jl, here are the sizes of the three dataframes in question:

• comp_df: 43 lines
• matching_comp_df: 42 lines
• trial_line_df: 200 lines

These are the settings I'm using:

param_to_sweep=:metabolic_rate 
start_value=1                  
end_value=50                   
num_values=50                  
trials_per_value=4             
graph_sweep=false