MPD.Simple: fix haddock link to MpdException
Add module headers
Unify timed and non-timed getResponse

Only provide a timed getResponse; let the user
indicate that no time-out is desired by supplying
a negative timeout.
MPD.Interact: implement keep-alive functionality

Adds a function keepAlive :: IO () -> IO () that runs
a computation (assumed to be some sort of bracket for
operating on a MPD connection handle), optimistically
retrying the computation if it throws an exception that
indicates a connection problem.

In the absence of connection related exceptions keepAlive f = f.
Add MPD.Procesing: combinators for processing response bodies

Do things like

    > map records . lists . responseBody
    >   <$> simpleMPD [ "status", "currentsong"]

to break the responses of status and currentsong
into separate sets of key/value records

or

    > values . responseBody <$> simpleMPD ["commands"]

to get a list of all command names.
Merge branches 'fix-haddock', 'module-headers', 'unify-timed-recv', 'processing' and 'keep-alive-2'

Conflicts:
	src/MPD.hs