[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/include/proto/proto_http.h b/include/proto/proto_http.h
index 298d30d..da4ea0e 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -58,7 +58,7 @@
 #define HTTP_IS_VER_TOKEN(x) (http_is_ver_token[(unsigned char)(x)])
 
 int event_accept(int fd);
-int process_session(struct task *t);
+void process_session(struct task *t, struct timeval *next);
 int process_cli(struct session *t);
 int process_srv(struct session *t);