Modifies quit to handle restarts and adds SIGHUP and SIGTERM handlers.

Modified quit() to restart if it receives arg .i = 1
MOD+CTRL+SHIFT+Q was added to confid.def.h to do just that.

Signal handlers were handled for SIGHUP and SIGTERM.
If dwm receives these signals it calls quit() with
arg .i = to 1 or 0, respectively.

To restart dwm:
MOD+CTRL+SHIFT+Q
or
kill -HUP dwmpid

To quit dwm cleanly:
MOD+SHIFT+Q
or
kill -TERM dwmpid

config.def.h

@@ -96,6 +96,7 @@ static const Key keys[] = {
 	TAGKEYS(                        XK_8,                      7)
 	TAGKEYS(                        XK_9,                      8)
 	{ MODKEY|ShiftMask,             XK_q,      quit,           {0} },
+	{ MODKEY|ControlMask|ShiftMask, XK_q,      quit,           {1} }, 
 };
 
 /* button definitions */