Remove ridiculous function limit. Happy day.

The most recent 3.1 firmware update allows 64k functions. Finally. According
to analytics data, it looks like some users are using versions that still
have the 768 limit. For now, I've tweaked the Makefile to enforce a limit
of 768 and removed the note from the README. By the time we run into 768,
we should be able to live with restricting ourselves to updated units that
allow at least 64k.
Only add the cookie value, not params, as a header.
Tweak advertisement for new remote protocol.

Add the new headers to the GDM advertisement, and start responding to
`/resources`.
Add basic query string parsing to request object.
Very basic subscribe/unsubscribe handling for new remote.

Introduce the new NowPlayingManager, mostly a skeleton for now. Create
the subscribe and unsubscribe request handlers, and trivially keep track
of subscribers inside the now playing manager.
Simplify home screen popping, eliminate circular reference.
Switch analytics to new school singleton.
Switch MyPlexManager to new school singleton.
Move GDM advertiser to new school singleton.
Move audio player to new style singleton.
POST timeline data in response to subscribe requests.

Any time a subscribe request comes in, POST the current timeline data to the
subscriber. The actual timeline data is still never updated, but the mechanics
are there.
Wire up audio player and send timeline info to subscribers.
Add support for audio seeking via remote control.
Add the rest of the basic audio playback commands.
Add support for basic navigation commands, using ECP.
Add navigation command for now playing screen.
Add navigation command for returning to home screen.
Wire up navigation remote commands for photo player.
Send timeline information for photos to subscribers.
Send video player timeline data to subscribers.