Implement editor.insertText and use it in the special chars dialog

[Frederico Caldeira Knabben]

We must have an insertText function which inserts plain text into the editor, contextual to the current selection.

This ticket is being opened because of [5273]. It fixes the undesired behavior we have in the insert special char dialog because of the usage of insertHtml. We should revert those changes and use the new insertText function instead.

[Garry Yao]

We'll be working on this at #5309.

[Garry Yao]

Defer as #5309 is not in 3.5.

[Garry Yao]

Move this back to 3.5 as it could be implemented as a separately thing and helps to work around issues like #4746.

[Tobiasz Cudnik]

It doesn't remove a selection content when used with CKEDITOR.editor#insertText. Although the Special Chars dialog removes such content.

Is this a correct behavior?

[Garry Yao]

New patch changes a bit the original way of handling line-breaks in plain text, the major problem for the original way of using enterKey was performance penalty.

[Tobiasz Cudnik]

It works fine in FF and IE, although in Webkit (Chrome) i've got an extra paragraph and the inline style if not preserved.

Steps

1. Use such content with the selection:

   <p>
   	This is some <strong>sample [text</strong>. You are using <a href="http://ckeditor.com/">CKEditor</a>.]</p>
   

2. Execute the command:

   CKEDITOR.instances.editor1.insertText('foo\nbar');
   

Result:

<p>
	This is some <strong>sample&nbsp;</strong>foo</p>
<p>
	bar</p>

[Garry Yao]

1. Extra paragraph issue: this's actually a regression from [5728], addressed in new patch;
2. No inline style issue: this been a webkit bug instead, but only happens with text with multiple lines, so we'd probably have to go the same way with Gecko because of this.

[Tobiasz Cudnik]

It works fine now, although i had some issues when applying the patch on the newest revision.

[Garry Yao]

Fixed with [6143], sample page updated with [6144].