Refinement for cross-plugin compatibility

Hi,

I am updating my DrawIt plugin to support front-end editing plugins like Beaver Builder, but I have notice one shortcoming with how Beaver Builder stores the source code. After an image is added via Beaver Builder, switching back to the normal backend editor does not preserve the typical “wp-image-#” class name for the images that were added. This is important for image-editing based plugins that rely on using that image id # in the class name for source identification / editing purposes. It seems that the desired behavior should be at a minimum to preserver that class name. I know that the class name is getting preserved on the Beaver Builder side of things, because if I open it back up via your plugin’s front-end editor, then the class name is there. It seems to just be something to do with when publishing the content that is gets removed by your plugin for the backend.

For example, when adding an image in Beaver Builder, then changing back to the backend editor, this is the img code:

<img title="drawing via beaver-builder" src="http://mdt.space/wp43_test_drawit_plugin/wp-content/uploads/2016/01/drawing-via-beaver-builder.png" alt="drawing-via-beaver-builder" width="143" height="123" />

When I open it up in your front-end editor, then I get what I would have expected in the backend editor:

<img class="aligncenter wp-image-53" title="drawing via beaver-builder" src="http://mdt.space/wp43_test_drawit_plugin/wp-content/uploads/2016/01/drawing-via-beaver-builder.png" alt="drawing-via-beaver-builder" width="143" height="123" />

https://wordpress.org/plugins/beaver-builder-lite-version/