fixing the draw_orthogonal_grid function

[sanika-n]

Bug

I noticed that using make_mpl_space_component to create a plot, always created weird patterns in the background when the model used orthogonal grids. The red dots are agents, but the gray patterns were actually the rendition of the orthogonal grid by the draw_orthogonal_grid function.

Before

The logic seems to be correct, but the grid is being drawn using ":", this makes it easy to confuse between the horizontal and the vertical lines causing visually confusing renditions. To resolve this, I just changed ":" to "-" in the code.

After

To replicate an issue of this kind you could change draw_grid to True in sugarspace

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 -2.6% [-4.1%, -1.3%]	🔵 -0.6% [-0.8%, -0.4%]
BoltzmannWealth	large	🔵 -2.1% [-4.6%, -0.4%]	🔵 -2.5% [-3.4%, -1.5%]
Schelling	small	🔵 +0.5% [+0.2%, +0.8%]	🔵 -0.3% [-0.4%, -0.2%]
Schelling	large	🔵 +0.9% [+0.4%, +1.3%]	🔵 +2.0% [+0.7%, +3.0%]
WolfSheep	small	🔵 -0.4% [-0.9%, +0.2%]	🔵 +0.0% [-0.3%, +0.4%]
WolfSheep	large	🔵 -1.1% [-2.4%, -0.0%]	🔵 -2.6% [-4.3%, -0.9%]
BoidFlockers	small	🔵 -2.5% [-2.9%, -2.0%]	🟢 -4.3% [-4.5%, -4.2%]
BoidFlockers	large	🔵 -2.3% [-2.8%, -1.9%]	🟢 -3.8% [-4.0%, -3.7%]