add redraw command for ui update

Mentioned in #92.

comp.go

@@ -39,6 +39,7 @@ var (
 		"delete",
 		"put",
 		"clear",
+		"redraw",
 		"renew",
 		"sync",
 		"echo",

doc.go

@@ -43,6 +43,7 @@ The following commands are provided by lf without default keybindings:
 
     sync    synchronizes yanked/deleted files with server
     echo    prints its arguments to the message line
+    redraw  renew ui elements and redraw the screen
     cd      changes working directory to its argument
     push    simulate key pushes given in its argument
 

docstring.go

@@ -47,6 +47,7 @@ The following commands are provided by lf without default keybindings:
 
     sync    synchronizes yanked/deleted files with server
     echo    prints its arguments to the message line
+    redraw  renew ui elements and redraw the screen
     cd      changes working directory to its argument
     push    simulate key pushes given in its argument
 

eval.go

@@ -391,6 +391,9 @@ func (e *callExpr) eval(app *app, args []string) {
 			app.ui.message = msg
 			log.Printf(msg)
 		}
+	case "redraw":
+		app.ui.sync()
+		app.ui.renew()
 	case "renew":
 		app.ui.sync()
 		app.ui.renew()