Remove refs to outdated writers in animation.py.

pymedia has not been updated for 18y, and swf (adobe flash) is also no
more.  Directly wrapping x264 could still be done but the comment
probably doesn't help much...

Author: anntzer

lib/matplotlib/animation.py

@@ -28,13 +28,6 @@
 subprocess_creation_flags = (
     subprocess.CREATE_NO_WINDOW if sys.platform == 'win32' else 0)
 
-# Other potential writing methods:
-# * http://pymedia.org/
-# * libming (produces swf) python wrappers: https://github.com/libming/libming
-# * Wrap x264 API:
-
-# (https://stackoverflow.com/q/2940671/)
-
 
 def adjusted_figsize(w, h, dpi, n):
     """