Merge pull request #37 from fonttools/extra-lxml

make lxml optional

Author: anthrotype

setup.py

@@ -19,8 +19,9 @@
     packages=find_packages("src"),
     include_package_data=True,
     python_requires=">=3.6",
-    install_requires=["fonttools[ufo,lxml] >= 3.34.0", "attrs >= 18.2.0"],
+    install_requires=["fonttools[ufo] >= 3.34.0", "attrs >= 18.2.0"],
     setup_requires=["setuptools_scm"],
+    extras_require={"lxml": ["lxml"]},
     classifiers=[
         "Development Status :: 4 - Beta",
         "Operating System :: OS Independent",