a2dp source: cleanup api, add minimal docu, update example

a2dp: handle signaling chanel release, fix event's meta type

a2dp source: remove unused sep variable

a2dp source: handle incoming connection, send event to client on signaling connection established

a2dp: remove checks on seid, and cid

a2dp: pass remote bd address on stream established event

Fix more warnings (mostly sign-compare)

avdtp/avrcp: log error on malloc failure

a2dp: remove address check

avdtp source pts tes: extend sbc encoder init with channel mode param

avdtp, avrcp: cleanup, added error handling, fixed pts test compilation

a2dp source demo: cleanup

avdtp source demo: fix avdtp cid, use local/remote seid

avdtp: introduced avdtp cid on connect; cmd functions return now status; use local and remote sedi in events instead of initiator and acceptor seid

a2dp sink: forward stream establish, start, pause, release

a2dp sink: start extracting code from demo to a2dp layer

a2dp: report required buffer size when too small

avdp: drop unistd.h include

fix warnings in bluedroid and avdtp

a2dp_sink: don't respond to pin code request

remove printf from library code

avdtp_source_demo: remove ring buffer, ...

avdtp: move read ring to uint8_t buffer to the app

star removing ring buffer

use intermidiate sbc storage