Makes exif fields real readonly not hidden

Hi tobiasb,

First, thank you for the patch and your patience.

But I can not apply the patch as is as most of users are pleased with the current behavior which should have be called 'exif hidden widget'...
But you are right, we must have an hidden metadata widget *and* a readonly metadata widget.
I am already working on it on 8.x branch where it is easier to implement due to clear separation
of concerns.
To make it maintainable, on branch 7.x, I have to extract widget logic in separate classes and use a common interface to manage them.

regards,

Implemented in 8.x-1.x version.
back port to 7.x-1.x in progress.

I was working on something for this on a separate issue but then found this one.

Here's what I came up with, it turns the fields into disabled text fields:

I also built a similar feature for EXIF Custom that's a little simpler: #2942048: Add "extra" field to show all available EXIF data

This makes the new field display optional and adds an option on the field widget form to control it.

The last patch didn't remove $element['#value'] so that the fields were blank, this fixes that mistake.

Doh, wrong patches.

The D7 version is no longer supported.