add builtin 'draw' command to update efficiently

comp.go

@@ -32,6 +32,7 @@ var (
 		"delete",
 		"put",
 		"clear",
+		"draw",
 		"redraw",
 		"reload",
 		"read",

doc.go

@@ -44,6 +44,7 @@ The following commands are provided by lf with default keybindings:
 
 The following commands are provided by lf without default keybindings:
 
+    draw    draw the ui
     sync    synchronizes yanked/deleted files with server
     echo    prints its arguments to the message line
     cd      changes working directory to its argument

docstring.go

@@ -48,6 +48,7 @@ The following commands are provided by lf with default keybindings:
 
 The following commands are provided by lf without default keybindings:
 
+    draw    draw the ui
     sync    synchronizes yanked/deleted files with server
     echo    prints its arguments to the message line
     cd      changes working directory to its argument

eval.go

@@ -339,6 +339,7 @@ func (e *callExpr) eval(app *app, args []string) {
 		if err := sendRemote("send sync"); err != nil {
 			app.ui.printf("clear: %s", err)
 		}
+	case "draw":
 	case "redraw":
 		app.ui.sync()
 		app.ui.renew()