added more flexible colorspace conversion method.
added method to get numpy array from frame, similar to pil.image from frame
example show frames using numpy and openCV
using first argument as video file path in example - to match other examples.
fixed typo
made frame.time_base accessible to user.
scale packet duration too
fixed typo
release gil on open
added average_rate
removed av_frame_get_best_effort_timestamp
added _flush_decoder_frames method
None flushes codec, like encoding
check frame counts
check frame counts against stream.frames
set pts of flushed frames if possible
matched dranger method pts closer
added frame seek example
seeking tests
Initialize global network.

This is recommended, since it avoids the overhead of implicitly doing
the setup for each session.
Support PIL or Pillow.

Clean up examples so that Pillow can be used rather than the deprecated
PIL library.