fix : Uncaught TypeError: file_exists is not a function when you pass the url param : "langCode"

[fabriceci]

It occurs when you pass the url param "langCode", the manager calls the function "file_exists" at the line 173 , but the function is defined at the line 301. You can test here http://fm.16mb.com/index.html?langCode=en

The following error is raised :

filemanager.js:150 Uncaught TypeError: file_exists is not a function

To solve, just put the function declaration before the line 173.

[psolom]

Thanks for your contribution!