python-incremental: new package

This is a new requirement for the Twisted package.

From the readme:

Incremental is a small library that versions your Python projects.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

lang/python/python-incremental/patches/001-omit-tests.patch

@@ -0,0 +1,11 @@
+--- a/setup.py
++++ b/setup.py
+@@ -32,7 +32,7 @@ setup(
+         "Programming Language :: Python :: 3.5",
+         "Programming Language :: Python :: 3.6",
+     ],
+-    packages=find_packages("src", exclude=("exampleproj",)),
++    packages=find_packages("src", exclude=("exampleproj", "*.tests", "*.tests.*")),
+     package_dir={"": "src"},
+     extras_require={
+         "scripts": [