af-binder: bug fix and feature improvements

af-binder: bug fix and feature improvements

fixes:
 - webkit connection on websockets (SPEC-821)
 - over allocation of sessions
 - send error reply for unreplied requests
 - unprefix event name
 - infinite loop when events overrun counter
 - better handling of NULL

improvements:
 - dump of stack on SIGABRT
 - facility afb_req_subcall_req
 - reduced verbosity
 - debugging enhanced: allow break after wait and call to 'personality'
 - documentation

Bug-AGL: SPEC-821

Change-Id: I90f16aca97613616e7f2fb4bb85c052ae16c0cde
Signed-off-by: José Bollo <jose.bollo@iot.bzh>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/10605
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>