Add function to plot all maps

[mhliu0001]

This PR adds the function to plot all maps used in the simulation of a context. Solves #105.

To use this feature:

import appletree as apt 
from appletree.plot import plot_maps
# Set up a context
context = apt.ContextRn220()

# Plot all maps (3D maps are skipped unless collapsed)
figures = plot_maps(context)

# Collapse a 3D map to 2D by averaging over the z axis
figures = plot_maps(context, collapse={"s1_correction": {"z": None}})

# Collapse with a range selection on z
figures = plot_maps(
    context,
    collapse={"s1_correction": {"z": (-100, -50)}},
)

# Save all figures to disk
plot_maps(
    context,
    collapse={"s1_correction": {"z": None}},
    save=True,
    save_path="./map_plots",
    fmt=["png", "pdf"],
)

[coveralls]

Pull Request Test Coverage Report for Build 21973345323

Details

• 135 of 199 (67.84%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.0%) to 83.232%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
appletree/plot.py	135	199	67.84%

Totals
Change from base Build 21965575783:	-1.0%
Covered Lines:	2606
Relevant Lines:	3131

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💛 - Coveralls