V4L2/epoll() bug fixed after upgrading kernel to 3.13, remove polling workaround

since ubuntu 12.04 users can reasonably upgrade to the 14.04 HWE
stack, for now at least we'll remove the polling-based workaround in
cs_disp. that way we can avoid needing to replicate (or factor out and
manage) the workaround globally. note that running 'boda capture' and
checking for any read_but_dropped_frames (should be 0) seems to be an
easy and robust way to check for the issue.
disp_util: remove more unused asio/pipe experimental code
namespace/using cleanups
factor out asio capture read idiom. still dup'd in setup/next_frame cases ...
display_pil: was broken; fix wrt disp_win api changes
display_pil: experiments with clean shutdown methods needed for
cs_disp/IPC modes. so far so good?
cs_disp: first pass at quit handling.

pretty ugly, probably needs cleanups. seems to work. note that proc
process prints timers of it's own if/when it finishes gracefully
... probably want to supress that for now. but it's not currently
configurable ... :/