BUG-396: Implement move output <RANDR-OUTPUT> command

Also add support for move output <up|down|left|right> and update
userguide about the new command.

docs/userguide

@@ -759,6 +759,11 @@ You can also switch to the next and previous workspace with the commands
 workspace 1, 3, 4 and 9 and you want to cycle through them with a single key
 combination.
 
+To move a container to another xrandr output such as +LVDS1+ or +VGA1+, you can
+use the +move output+ command followed by the name of the target output. You
+may also use +left+, +right+, +up+, +down+ instead of the xrandr output name to
+move to the the next output in the specified direction.
+
 *Examples*:
 -------------------------
 bindsym mod+1 workspace 1

src/cmdparse.l

@@ -123,6 +123,7 @@ floating                        { return TOK_FLOATING; }
 toggle                          { return TOK_TOGGLE; }
 mode_toggle                     { return TOK_MODE_TOGGLE; }
 workspace                       { WS_STRING; return TOK_WORKSPACE; }
+output                          { WS_STRING; return TOK_OUTPUT; }
 focus                           { return TOK_FOCUS; }
 move                            { return TOK_MOVE; }
 open                            { return TOK_OPEN; }

src/cmdparse.y

@@ -149,6 +149,7 @@ bool definitelyGreaterThan(float a, float b, float epsilon) {
 %token              TOK_ENABLE          "enable"
 %token              TOK_DISABLE         "disable"
 %token              TOK_WORKSPACE       "workspace"
+%token              TOK_OUTPUT          "output"
 %token              TOK_TOGGLE          "toggle"
 %token              TOK_FOCUS           "focus"
 %token              TOK_MOVE            "move"
@@ -704,6 +705,51 @@ move:
 
         tree_render();
     }
+    | TOK_MOVE TOK_OUTPUT STR
+    {
+        owindow *current;
+
+        printf("should move window to output %s", $3);
+
+        HANDLE_EMPTY_MATCH;
+
+        /* get the output */
+        Output *current_output = NULL;
+        Output *output;
+
+        TAILQ_FOREACH(current, &owindows, owindows)
+            current_output = get_output_containing(current->con->rect.x, current->con->rect.y);
+
+        assert(current_output != NULL);
+
+        if (strcasecmp($3, "up") == 0)
+            output = get_output_next(D_UP, current_output);
+        else if (strcasecmp($3, "down") == 0)
+            output = get_output_next(D_DOWN, current_output);
+        else if (strcasecmp($3, "left") == 0)
+            output = get_output_next(D_LEFT, current_output);
+        else if (strcasecmp($3, "right") == 0)
+            output = get_output_next(D_RIGHT, current_output);
+        else
+            output = get_output_by_name($3);
+        free($3);
+
+        if (!output)
+            return 0;
+
+        /* get visible workspace on output */
+        Con *ws = NULL;
+        GREP_FIRST(ws, output_get_content(output->con), workspace_is_visible(child));
+        if (!ws)
+            return 0;
+
+        TAILQ_FOREACH(current, &owindows, owindows) {
+            printf("matching: %p / %s\n", current->con, current->con->name);
+            con_move_to_workspace(current->con, ws);
+        }
+
+        tree_render();
+    }
     ;
 
 append_layout: