bitstream: new package

BiTStream is a set of headers to ease processing of mpeg ts
streams. It is used by dvblast.

[Thomas:
 - add missing hash file.
 - add missing BITSTREAM_LICENSE_FILES information.
 - rewrap Config.in help text.
 - use lowercase name for the package in the comment header in
   bitstream.mk.]

Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>