MAINTENANCE: Automated closing of pull requests.

This commit exists to close the following pull requests on Github:

Closes #930 (close requested by 'andrewor14')
Closes #867 (close requested by 'marmbrus')
Closes #1829 (close requested by 'marmbrus')
Closes #1131 (close requested by 'JoshRosen')
Closes #1571 (close requested by 'andrewor14')
Closes #2359 (close requested by 'andrewor14')