Fix #55

Primarily, this involves getting the parent classes in the right order
for the raw encoders
xfail raw tests correctly
Remove redundant link
Tweak tests setup

Removed coverage (as the pytest coverage plugin is just broken and we
don't care much about coverage in this project anyway), fixed a silly
issue in the extra-requires, and moved the test deps there too. Tweaked
the Makefile to use pip to install in a development environment in the
hopes that when pip gets updated to 1.4 we'll be able to use it to pull
in the test dependencies automatically too
Fix #54

Minor change to the docs - hopefully this is enough to clarify things
for Mac OS X users (I've had a brief read on the differences between
MacPorts and Homebrew - given Homebrew's reliance on system installed
stuff, and installation into default PATH locations I'm hoping I'm
correct in excluding it from the "extra instructions")

Also modified the recipe to pre-split the command line. This should fix
things for Windows users who commonly have spaces in the path to things
like VLC or mplayer...
Fix reference to easy_install

Should be pip for py2
Fix #58
Fix #56

Implements the ability to specify the video-port splitter to use for
video-recording and video-port based image capture. The frame property
is now a bit of a fudge, but still compatible with existing code.
Fix a race condition in capture_continuous

Looks like there's been a long standing race condition in the
capture_continuous method; because the encoder's stop() method isn't
called until the loop is broken, and because the encoder's wait() method
doesn't call _close_output() it was possible to attempt to access a
captured image in the loop before it was fully flushed to disk.