restartsig patch

- Apply restartsig patch
- Add keybinding for restarting dwm
- Update man page with keybinding
- Update README with patch link

dwm.c

@@ -240,6 +240,8 @@ static void setup(void);
 static void seturgent(Client *c, int urg);
 static void showhide(Client *c);
 static void sigchld(int unused);
+static void sighup(int unused);
+static void sigterm(int unused);
 static void spawn(const Arg *arg);
 static Monitor *systraytomon(Monitor *m);
 static void tag(const Arg *arg);
@@ -316,6 +318,7 @@ static void (*handler[LASTEvent]) (XEvent *) = {
 	[UnmapNotify] = unmapnotify
 };
 static Atom wmatom[WMLast], netatom[NetLast], xatom[XLast];
+static int restart = 0;
 static int running = 1;
 static Cur *cursor[CurLast];
 static Clr **scheme;
@@ -1456,6 +1459,7 @@ propertynotify(XEvent *e)
 void
 quit(const Arg *arg)
 {
+	if(arg->i) restart = 1;
 	running = 0;
 }
 
@@ -1900,6 +1904,9 @@ setup(void)
 	/* clean up any zombies immediately */
 	sigchld(0);
 
+	signal(SIGHUP, sighup);
+	signal(SIGTERM, sigterm);
+
 	/* init screen */
 	screen = DefaultScreen(dpy);
 	sw = DisplayWidth(dpy, screen);
@@ -2009,6 +2016,20 @@ sigchld(int unused)
 	while (0 < waitpid(-1, NULL, WNOHANG));
 }
 
+void
+sighup(int unused)
+{
+	Arg a = {.i = 1};
+	quit(&a);
+}
+
+void
+sigterm(int unused)
+{
+	Arg a = {.i = 0};
+	quit(&a);
+}
+
 void
 spawn(const Arg *arg)
 {
@@ -2691,6 +2712,7 @@ main(int argc, char *argv[])
 	runautostart();
 	run();
 	runautoquit();
+	if(restart) execvp(argv[0], argv);
 	cleanup();
 	XCloseDisplay(dpy);
 	return EXIT_SUCCESS;