Since 1.8, the new pickupsound and pickupfailsound in features.conf cause many issues.

1). chan_sip:handle_request_invite() shouldn't be playing out the fail/success audio, as it has 'netlock' locked.
2). dialplan applications for directed_pickups shouldn't beep.
3). feature code for directed pickup should beep on success/failure if configured.

Moved app_directed:pickup_do() to features:ast_do_pickup().

Functions below, all now use the new ast_do_pickup()
app_directed_pickup.c:
   pickup_by_channel()
   pickup_by_exten()
   pickup_by_mark()
   pickup_by_part()
features.c:
   ast_pickup_call()

Created a sip_pickup() thread to handle the pickup and playout the audio, spawned from handle_request_invite.

pickup using *8 feature code, with pickup sounds enabled/disabled

exten => 71,1,Pickup()           ; any ringing extension in same pickupgroup 
exten => 72,1,Pickup(85@phones)  ; dahdi extension
exten => 73,1,Pickup(823@phones) ; sip extension