Port DragResizeTable to V3

[alfonsoml]

Several people have requested the upgrade of this plugin

[garry.yao]

The patch recreated the v2 plugin with the same functionality.

[fredck]

• This one is supposed to be an extra plugin, not included in the default list of plugins.

• Let's also separate things a bit, to not make the core bloated. The buildTableMap function can even be appended to the CKEDITOR.tools object, but it should still be defined in the tabletools plugin. That plugin will then enter in the requires list for the tableresize plugin.

In the plugin code:

• We don't need to have those functions defined in the private "_" property of the ColumnResizer class. I believe most of them can be private functions in the main anonymous function.

• The class name should be columnResizer.

• Instead of editor.document.$.documentElement, you should use ​editor.document.getDocumentElement().

• There are some jslint warnings in the code.

• It happens to have decimal precision in the sizes, like "42.5px". Let's round them to have only integers.

[garry.yao]

We don't need to have those functions defined in the private "_" property of the ColumnResizer class.

I don't see problems in this case, since they're event handlers that bind to the columnResizer instance, scoping them as closure bring runtime performance penalty as well.

[fredck]

Replying to garry.yao:

I don't see problems in this case, since they're event handlers that bind to the columnResizer instance,

The benefit of having them our of the "_" is that the code will compact much better on release. Other than having the function names reduced, their calls will result very shorter.

scoping them as closure bring runtime performance penalty as well.

Yes, a book theory. You'll never be able to demonstrate it in this specific case.

[garry.yao]

New patch with the following points addressed:

1. Performance: Pillar discovery algorithm reduced from O(n²) to linear with table pillar caching enable;
2. Better code packings, 0.8K reduced by utilizing module pattern.

[fredck]

The performance enhancements are noticeable, and wonderful. Congratulations for it.

Please have this one committed into the 3.4.x branch.

[garry.yao]

Fixed with [5572] on 3.4.x branch.