cleanup: remote obsolete references to listening_ip
albumart: code simplification
status: note when a media scan is in progress
Use SERVER_NAME variable when checking for existing process.
Fix Broken SSDP Multicast Membership Addition.
upnpsoap: fix uninitialized read with emtpy filter
Introduce THISORNUL macro.
Fix various potential illegal access and memory leaks in error conditions.
process: remove logically dead code.
Clean up a couple return value checks.
Fix typo in multi content type example
upnphttp: check realloc return while receiving headers
upnphttp: limit receive headers size to 1 MB
upnphttp: check realloc return while receiving request body
upnphttp: improve robustness against malformed (possibly malicious) requests
Declare printf-like attributes for strcatf() and xasprintf()

Declare printf-like attributes for strcatf() and xasprintf(), and
clean up errors found by the compile after doing so.
Add printf attribute to log_err/DPRINTF and fix a few warnings

Modified to not use %z for portability reasons.