Implement deprecated new_window and new_float commands

May as well make it as easy as possible for users who are coming from
i3.

This also changes the `border` command to accept a thickness when
setting the border to normal. This makes it work the same way as the
`default_border` command. Eg. `border normal 5`

sway/commands.c

@@ -118,6 +118,8 @@ static struct cmd_handler handlers[] = {
 	{ "input", cmd_input },
 	{ "mode", cmd_mode },
 	{ "mouse_warping", cmd_mouse_warping },
+	{ "new_float", cmd_default_floating_border },
+	{ "new_window", cmd_default_border },
 	{ "no_focus", cmd_no_focus },
 	{ "output", cmd_output },
 	{ "seat", cmd_seat },

sway/commands/border.c

@@ -27,9 +27,6 @@ struct cmd_results *cmd_border(int argc, char **argv) {
 		view->border = B_NORMAL;
 	} else if (strcmp(argv[0], "pixel") == 0) {
 		view->border = B_PIXEL;
-		if (argc == 2) {
-			view->border_thickness = atoi(argv[1]);
-		}
 	} else if (strcmp(argv[0], "toggle") == 0) {
 		view->border = (view->border + 1) % 3;
 	} else {
@@ -37,6 +34,9 @@ struct cmd_results *cmd_border(int argc, char **argv) {
 				"Expected 'border <none|normal|pixel|toggle>' "
 				"or 'border pixel <px>'");
 	}
+	if (argc == 2) {
+		view->border_thickness = atoi(argv[1]);
+	}
 
 	if (container_is_floating(view->swayc)) {
 		container_set_geometry_from_floating_view(view->swayc);