Add travis job to publish on PyPI.

Also moved some shortcuts into manimlib, to be able to use it without the big_ol_pile_of_manim_imports script. Updated the README to explain installation via pip

manim.py

@@ -1,17 +1,7 @@
 #!/usr/bin/env python
-import manimlib.config
-import manimlib.extract_scene
-import manimlib.stream_starter
+import manimlib
 
 if __name__ == "__main__":
-    args = manimlib.config.parse_cli()
-    if not args.livestream:
-        config = manimlib.config.get_configuration(args)
-        manimlib.extract_scene.main(config)
-    else:
-        manimlib.stream_starter.start_livestream(
-            to_twitch=args.to_twitch,
-            twitch_key=args.twitch_key,
-        )
+    manimlib.main()
 else:
     manimlib.stream_starter.start_livestream()