[mythtv-cmyth] Dedicated control connection for recording file

- MythFile references the cmyth control connection to use.
- MythProgramInfo: Add Host() and Port() to connect control connection. Host and port could be different of addon Myth server ?
- MythConnection: Initialize dedicated control connection for recording file.
[cmyth] Align buffer sizes

This adds a buflen parameter to cmyth_livetv_chain_setup to specify
the receive buffer from outside.

In addition this removes setting tcp_buflen to the value returned by
getsockopt(SO_RCVBUF). The reason is that getsockopt will return different
values depending on the platform. Linux systems double the value since
they reserve half of the buffer for metadata. Other systems don't do this
and since that value is reused as input for setsockopt when starting playback,
we create buffers of the doubled size.
[mythtv-cmyth] Define common size of all RCV and TCP RCV buffers

This defines a common tcp buffer size of 128000 (from MythTV).
Ihe internal buffers used for receiving the data is set to the same value.

Conflicts:

	addons/pvr.mythtv.cmyth/src/cppmyth/MythConnection.cpp
[mythtv-cmyth] Force buflen for chain, file and path to 64 bytes

- Buffer is only used to receive backend response of query ANN FileTransfer. So fix buflen to 64 bytes during setup.