[MAJOR] replaced all timeouts with struct timeval

The timeout functions were difficult to manipulate because they were
rounding results to the millisecond. Thus, it was difficult to compare
and to check what expired and what did not. Also, the comparison
functions were heavy with multiplies and divides by 1000. Now, all
timeouts are stored in timevals, reducing the number of operations
for updates and leading to cleaner and more efficient code.
diff --git a/src/queue.c b/src/queue.c
index 9b53687..37d3ed8 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -45,9 +45,9 @@
 /*
  * Manages a server's connection queue. If woken up, will try to dequeue as
  * many pending sessions as possible, and wake them up. The task has nothing
- * else to do, so it always returns TIME_ETERNITY.
+ * else to do, so it always returns ETERNITY.
  */
-int process_srv_queue(struct task *t)
+void process_srv_queue(struct task *t, struct timeval *next)
 {
 	struct server *s = (struct server*)t->context;
 	struct proxy  *p = s->proxy;
@@ -65,7 +65,7 @@
 		task_wakeup(sess->task);
 	}
 
-	return TIME_ETERNITY;
+	tv_eternity(next);
 }
 
 /* Detaches the next pending connection from either a server or a proxy, and