Added option random_cb for images in edit fields

[niahoo]

Hi,

this is a small addition to let the developer generate image names.

I wanted to add a function possible value to the naming option and add a naming_cb option, but this requires some refactoring to keep the code clean*.

So, this just adds the possibility to provide a callback, but it is of-course not mandatory for the callback to provide actual-random names. (md5 of the file content is what I personnally do !).

Also if you like this and would rather set the defaults-options/rules in the Field\File class, just tell me.

(* I wish that Multup does not generate names by itself, only using the callbacks it's given or a name (string) it's given.)

[niahoo]

Hi, could you tell me if you're interested or not ?

[davemathews]

@niahoo I'm interested just trying to decide the full need v/s if this is the best way.

[niahoo]

The full need is to be able to specify the file name with a function. The best thing to do imho is to allow a function as a value for the naming option.

I can code that if you want.