Revert "Remove use of setuptools Feature. Fixes #23"
Revert "Remove use of setuptools Feature. Fixes #23"

This reverts commit b74cfd1f7ab5a82b2d0bf96f750998bc66324034.

pallets/markupsafe,mitsuhiko/markupsafe,mitsuhiko/markupsafe,pallets/markupsafe