Make manim installable using setuptools (setup.py)

Now you an install it into the system packages and use it outside the
source code directory.

setup.py

@@ -0,0 +1,25 @@
+from setuptools import setup, find_namespace_packages
+
+
+setup(name='manim',
+      version='0.1.0',
+      description='Animation engine for explanatory math videos',
+      author='Grant Sanderson',
+      author_email='grant@3blue1brown.com',
+      url='https://github.com/3b1b/manim',
+      license='MIT',
+      packages=find_namespace_packages(),
+      install_requires=[
+         'colour',
+         'numpy',
+         'Pillow',
+         'progressbar',
+         'scipy',
+         'tqdm',
+         'opencv-python',
+         'pycairo',
+         'pydub',
+      ],
+      scripts=['manim.py', 'stage_scenes.py', 'big_ol_pile_of_manim_imports.py'],
+      package_data={'manimlib': ['*.tex', 'files/**']},
+)