Apply movestack patch

- Add keybinds to switch window between master and slaves
- Add movestack.c

config.h

@@ -1,5 +1,8 @@
 /* See LICENSE file for copyright and license details. */
 
+/* includes */
+#include "movestack.c"
+
 /* appearance */
 static const unsigned int borderpx  = 2;        /* border pixel of windows */
 static const unsigned int snap      = 32;       /* snap pixel */
@@ -80,6 +83,8 @@ static Key keys[] = {
 	{ MODKEY,                       XK_d,      		incnmaster,     {.i = -1 } },
 	{ MODKEY,                       XK_h,      		setmfact,       {.f = -0.05} },
 	{ MODKEY,                       XK_l,      		setmfact,       {.f = +0.05} },
+	{ MODKEY|ShiftMask,             XK_j,      		movestack,      {.i = +1 } },
+	{ MODKEY|ShiftMask,             XK_k,      		movestack,      {.i = -1 } },
 	{ MODKEY,                       XK_Return, 		zoom,           {0} },
 	{ MODKEY,                       XK_Tab,    		view,           {0} },
 	{ MODKEY|ShiftMask,             XK_c,      		killclient,     {0} },

movestack.c

@@ -0,0 +1,48 @@
+void
+movestack(const Arg *arg) {
+	Client *c = NULL, *p = NULL, *pc = NULL, *i;
+
+	if(arg->i > 0) {
+		/* find the client after selmon->sel */
+		for(c = selmon->sel->next; c && (!ISVISIBLE(c) || c->isfloating); c = c->next);
+		if(!c)
+			for(c = selmon->clients; c && (!ISVISIBLE(c) || c->isfloating); c = c->next);
+
+	}
+	else {
+		/* find the client before selmon->sel */
+		for(i = selmon->clients; i != selmon->sel; i = i->next)
+			if(ISVISIBLE(i) && !i->isfloating)
+				c = i;
+		if(!c)
+			for(; i; i = i->next)
+				if(ISVISIBLE(i) && !i->isfloating)
+					c = i;
+	}
+	/* find the client before selmon->sel and c */
+	for(i = selmon->clients; i && (!p || !pc); i = i->next) {
+		if(i->next == selmon->sel)
+			p = i;
+		if(i->next == c)
+			pc = i;
+	}
+
+	/* swap c and selmon->sel selmon->clients in the selmon->clients list */
+	if(c && c != selmon->sel) {
+		Client *temp = selmon->sel->next==c?selmon->sel:selmon->sel->next;
+		selmon->sel->next = c->next==selmon->sel?c:c->next;
+		c->next = temp;
+
+		if(p && p != c)
+			p->next = c;
+		if(pc && pc != selmon->sel)
+			pc->next = selmon->sel;
+
+		if(selmon->sel == selmon->clients)
+			selmon->clients = c;
+		else if(c == selmon->clients)
+			selmon->clients = selmon->sel;
+
+		arrange(selmon);
+	}
+}