[-] MO : blocktopmenu: fixed bug when editing links labels with special ...

Fixes a bug that occurs when editing links' labels that contain special characters (like óöñ...)

To reproduce bug:

1. Create a link containing special chars
![captura de pantalla 2014-08-21 a la s 19 42 19](https://cloud.githubusercontent.com/assets/389613/4000549/d3301316-295a-11e4-98f2-bd649751e095.png)

1. Click on modify
![captura de pantalla 2014-08-21 a la s 19 42 40](https://cloud.githubusercontent.com/assets/389613/4000554/e05e00de-295a-11e4-9089-72465f6338a4.png)

2. And you get a lot of HTML entities that will appear on frontend
![captura de pantalla 2014-08-21 a la s 19 42 51](https://cloud.githubusercontent.com/assets/389613/4000559/ee1f027c-295a-11e4-82a8-88f3c6921d3c.png)

Hi,

I believe there's no need to call twice Tools::htmlentitiesDEcodeUTF8() here. Call it just one time and you get the desired result

Best regards,