ENH: support MultiPolygons

[martinfleis]

Do not error on MultiPolygons in Corners and CentroidCorners. Untested but that is fine for now.

[codecov]

Codecov Report

Merging #234 (47958a7) into master (d296118) will decrease coverage by 0.87%.
The diff coverage is 62.66%.

@@            Coverage Diff             @@
##           master     #234      +/-   ##
==========================================
- Coverage   96.92%   96.05%   -0.88%     
==========================================
  Files          12       12              
  Lines        2634     2660      +26     
==========================================
+ Hits         2553     2555       +2     
- Misses         81      105      +24     

Impacted Files	Coverage Δ
momepy/intensity.py	98.52% <ø> (ø)
momepy/preprocessing.py	92.85% <ø> (ø)
momepy/shape.py	90.60% <62.66%> (-5.13%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d296118...47958a7. Read the comment docs.