added missing shapefile group to download script

[georgemccabe]

Rationale

Using cartopy.features.STATES with matplotlib causes an error because the shapefile group that is used is not available. Adding these missing groups to the download script will allow it to be used to obtain the files needed to run.

The group that is used to draw state/province boundaries is admin_1_states_provinces_lakes:

cartopy/lib/cartopy/feature/__init__.py

Lines 482 to 484 in 859f15b

	STATES = NaturalEarthFeature(
	'cultural', 'admin_1_states_provinces_lakes',
	auto_scaler, edgecolor='black', facecolor='none')

The files are available in the new location on the web:

https://naturalearth.s3.amazonaws.com/50m_cultural/ne_50m_admin_1_states_provinces_lakes.zip
https://naturalearth.s3.amazonaws.com/110m_cultural/ne_110m_admin_1_states_provinces_lakes.zip

Implications

Additional files will be downloaded when a user runs the script specifying the 'cultural-extra' group. However, these files are very small.

I tested the changes by obtaining the script from my branch and running it, then rerunning the use case that was failing. I confirmed that the use case now runs without error.

[georgemccabe]

Here is an example I used to recreate this error. It is using cartopy==0.18.0 and matplotlib==3.3.0.

import matplotlib.pyplot as plt
import cartopy.feature as cfeature
import cartopy.crs as ccrs

fig = plt.figure(figsize=(10,10))
proj = ccrs.PlateCarree(central_longitude=60)
ax1 = fig.add_subplot(5,2,1,projection=proj)
ax1.add_feature(cfeature.STATES)
plt.savefig('test.png',format='png',dpi=400, bbox_inches='tight')

The commands work fine if the line that adds the feature cfeature.STATES is removed.

I downloaded the cartopy_feature_download.py script from the master branch of SciTools/cartopy and ran with the 'cultural-extra' argument. I reran the commands and still received the error. Next I downloaded the script from my fork, ran it again to get the missing shapefiles, and reran the commands. This time there were no errors.

[dopplershift]

Changes look good, thanks for the contribution. Just waiting on the CLA to be signed.

[georgemccabe]

Changes look good, thanks for the contribution. Just waiting on the CLA to be signed.

Thanks! I signed the CLA. I committed the suggestion from @greglucas to obtain all scales for the new shapefiles group instead of listing out the 2 that I needed. This seems like a cleaner solution. I tested the change locally and it obtained the 10m scale as well.