Bugfix for infinite loop

The first two commits are a rollback of my previous proposal and merge with your changes.

The second tries to make the timeout calculations unified in all places and avoids the % in favor of * and -.

The third commit fixes a corruption of the linked list - there are several issues:

- send_ping removes the entry from the list and if the entry is already dequeued it will corrupt the list on error
- dequeue and remove do not modify ev_next and ev_prev while the functions that add items to the list rely on NULL values

In the output below it is clearly seen how the list is converted to a circle with all ev_prev==NULL

(gdb) print num_timeout 
$27 = 36457670
(gdb) print num_jobs 
$28 = -36457671
(gdb) print *ev_first
$29 = {ev_prev = 0x0, ev_next = 0x1ba67a0, ev_time = {tv_sec = 1337617783, tv_usec = 810555}, ev_type = 2, i = 2, 
  name = 0x1ba65c0 "192.168.241.21", host = 0x1ba65c0 "192.168.241.21", pad = 0x0, saddr = {sin_family = 2, sin_port = 0, 
    sin_addr = {s_addr = 368158912}, sin_zero = "\000\000\000\000\000\000\000"}, timeout = 150, running = 0 '\000', 
  waiting = 0 '\000', last_send_time = {tv_sec = 1337617783, tv_usec = 809055}, num_sent = 2, num_recv = 0, max_reply = 0, 
  min_reply = 10000000, total_time = 0, num_sent_i = 2, num_recv_i = 0, max_reply_i = 0, min_reply_i = 0, total_time_i = 0, 
  resp_times = 0x1ba6680}
(gdb) print *ev_first->ev_next
$30 = {ev_prev = 0x0, ev_next = 0x1ba6880, ev_time = {tv_sec = 1337617783, tv_usec = 812616}, ev_type = 2, i = 4, 
  name = 0x1ba6780 "192.168.253.9", host = 0x1ba6780 "192.168.253.9", pad = 0x0, saddr = {sin_family = 2, sin_port = 0, sin_addr = {
      s_addr = 167618752}, sin_zero = "\000\000\000\000\000\000\000"}, timeout = 100, running = 0 '\000', waiting = 0 '\000', 
  last_send_time = {tv_sec = 1337617783, tv_usec = 811116}, num_sent = 2, num_recv = 2, max_reply = 3853, min_reply = 3742, 
  total_time = 7595, num_sent_i = 2, num_recv_i = 2, max_reply_i = 3853, min_reply_i = 0, total_time_i = 7595, 
  resp_times = 0x1ba6840}
(gdb) print *ev_first->ev_next->ev_next
$31 = {ev_prev = 0x0, ev_next = 0x1ba65e0, ev_time = {tv_sec = 1337617783, tv_usec = 813672}, ev_type = 2, i = 5, 
  name = 0x1ba6860 "192.168.242.20", host = 0x1ba6860 "192.168.242.20", pad = 0x0, saddr = {sin_family = 2, sin_port = 0, 
    sin_addr = {s_addr = 351447232}, sin_zero = "\000\000\000\000\000\000\000"}, timeout = 150, running = 0 '\000', 
  waiting = 0 '\000', last_send_time = {tv_sec = 1337617783, tv_usec = 812172}, num_sent = 2, num_recv = 0, max_reply = 0, 
  min_reply = 10000000, total_time = 0, num_sent_i = 2, num_recv_i = 0, max_reply_i = 0, min_reply_i = 0, total_time_i = 0, 
  resp_times = 0x1ba6920}
(gdb) print *ev_first->ev_next->ev_next->ev_next
$32 = {ev_prev = 0x0, ev_next = 0x1ba67a0, ev_time = {tv_sec = 1337617783, tv_usec = 810555}, ev_type = 2, i = 2, 
  name = 0x1ba65c0 "192.168.241.21", host = 0x1ba65c0 "192.168.241.21", pad = 0x0, saddr = {sin_family = 2, sin_port = 0, 
    sin_addr = {s_addr = 368158912}, sin_zero = "\000\000\000\000\000\000\000"}, timeout = 150, running = 0 '\000', 
  waiting = 0 '\000', last_send_time = {tv_sec = 1337617783, tv_usec = 809055}, num_sent = 2, num_recv = 0, max_reply = 0, 
  min_reply = 10000000, total_time = 0, num_sent_i = 2, num_recv_i = 0, max_reply_i = 0, min_reply_i = 0, total_time_i = 0, 
  resp_times = 0x1ba6680}