A memcached client that internally uses libev

Examples:

>>> from memcev import Client
>>> c = Client('localhost', 11211)

>>> print c.get('doesntexist')
None

>>> c.set('foo', 'bar')
>>> print c.get('foo')
bar

Known issues:

• single server, no distribution
• string values only
• no compression
• only get and set. No get_multi/set_multi etc
• issuing a stop() will cause anyone in other threads that are blocked on a response to sleep for forever. not a big deal since it's only really called on dealloc
  • could fix this by keeping track of all sleeping clients
• we require Python 2.7 because we use the capsule API
• we don't really handle EINTR, except where libev does it for us
• we don't really handle timeouts at any point in the stack except connections
• we don't really handle errors that require a reconnect. you just lose the connection. in fact, libev only seems to tell us about certain errors so there may be others that go unreported until a socket read/write fails, which we then also fail to handle :)
• we aren't ready for Python 3
• our set of valid memcached keys is more restrictive than memcached's
• we don't work without EV_MULTIPLICITY
• there's no exception hierarchy, you just get "Exception"
• we make no effort to deal with broken or malicious servers that could cause us to block forever or use up all of our memory with long, invalid responses