Stomp queue restructuring for mass scalability:

- Multiplexing queues into groups and for multiple sites.
- Sharing vs breakout configurable per site and per queue via $config['queue']['breakout']
- Detect how many times a message is redelivered, discard if it's killed too many daemons
 - count configurable with $config['queue']['max_retries']
 - can dump the items to files in $config['queue']['dead_letter_dir']

Queue daemon memory & resource leak fixes:
- avoid unnecessary reconnections to memcached server (switch persistent connections back in on second initialization, assuming it's child process)
- monkey-patch for leaky .ini loads in DB_DataObject::databaseStructure() - was leaking 200k per active switch
- applied leak fixes to Status_network as well, using intermediate base Safe_DataObject for both it and Memcache_DataObject

Misc queue fixes:
- correct handling of child processes exiting due to signal termination instead of regular exit
- shutdown instead of infinite respawn loop if we're already past the soft memory limit at startup
- Added --all option for xmppdaemon... still opens one xmpp connection per site that has xmpp active

Cache updates:
- add Cache::increment() method with native support for memcached atomic increment

lib/spawningdaemon.php

@@ -90,18 +90,24 @@ abstract class SpawningDaemon extends Daemon
         while (count($children) > 0) {
             $status = null;
             $pid = pcntl_wait($status);
-            if ($pid > 0 && pcntl_wifexited($status)) {
-                $exitCode = pcntl_wexitstatus($status);
-
+            if ($pid > 0) {
                 $i = array_search($pid, $children);
                 if ($i === false) {
-                    $this->log(LOG_ERR, "Unrecognized child pid $pid exited with status $exitCode");
+                    $this->log(LOG_ERR, "Ignoring exit of unrecognized child pid $pid");
                     continue;
                 }
+                if (pcntl_wifexited($status)) {
+                    $exitCode = pcntl_wexitstatus($status);
+                    $info = "status $exitCode";
+                } else if (pcntl_wifsignaled($status)) {
+                    $exitCode = self::EXIT_ERR;
+                    $signal = pcntl_wtermsig($status);
+                    $info = "signal $signal";
+                }
                 unset($children[$i]);
 
                 if ($this->shouldRespawn($exitCode)) {
-                    $this->log(LOG_INFO, "Thread $i pid $pid exited with status $exitCode; respawing.");
+                    $this->log(LOG_INFO, "Thread $i pid $pid exited with $info; respawing.");
 
                     $pid = pcntl_fork();
                     if ($pid < 0) {