[mythtv] MHEG BBC iPlayer

[Lawrence Rust]

Hi,

I've been working on the MHEG code to add support for "Interaction
Channel" (ETSI ES 202 184 V2.2.1) which enables BBC iPlayer and other
http based interactive content to be accessed directly from the "Red
button",  For anyone interested in trying, I have a patch here: 

http://www.softsystem.co.uk/download/mythtv/iplayer.diff

for the current MythTV 0.24.1.  The patch covers 4 main areas:

1. libfreemheg - includes the new ASN functions and http files & streams
2. mhi - supports http files & streams and additional input keys
3. MythPlayer - additional API to support mhi stream selection
4. RingBuffer - supports reading from a URI and a few bug fixes.

After the patch is applied, rebuild and restart mythfrontend.  Wait for
the red button prompt which should now show "BBC iPlayer" if all is
well.

The interaction channel can be disabled by setting:
MYTHMHEG=noice

Additionally, the http client can be made to use a proxy, for instance
tor, by setting:
MYTHMHEG_PROXY="socks://localhost:9050"

Apologies for not providing a patch for git master, but my production
backend (which has my only dvb-s feed) runs 0.24.1.  A patch for master
is not too onerous.

Comments, criticisms and suggestions most welcome.

-- 
Lawrence Rust