Implement ShowBorders

[alfonsoml]

Implement the ShowBorders feature.

Instead of being only a configuration option, I think that it would be much better if it was possible to use it as a command, so the people could opt to put it in the toolbar

[garry.yao]

Implement it as a command, and I'm currently disabled it in IE, with the concern of the implementation based on HTC would not accepted here. We may even considering a datafilter rule for IE.

[fredck]

It must also work with IE.

Also, the borderStyleRegex replacement is not necessary as we have it just once in the template.

[garry.yao]

Manual TCs added at :  http://ckeditor.t/tt/4341/1.html

[fredck]

• There should be no changes to the config.js file as those are plugin specific settings.

• In any case, the effective code definition of startupShowBorders is not needed. It should be a "documentation only" definition, just like the dialog plugin settings.

• What about IE6? If I can make it there (V2) I can make it everywhere, right?

[garry.yao]

As discussed with Fred today, as we have almost complete control over the editor input, we could innovate a bit by simply using a css marker class for showborders style instead of the solution based on selectors and HTC before.
New Ticket Test added at :
 http://ckeditor.t/tt/4341/2.html.  http://ckeditor.t/tt/4341/3.html.

[fredck]

#4735 has been marked as DUP.

[fredck]

There is a typo in line 21 (an extra comma), which breaks the feature in IE6. Please fix it before committing.

[garry.yao]

Nice catch[[BR]] Fixed with [4568] and [4569].