Allow placing the annotation element after the selected text

[daliboris]

In the annotation view, inserted <pb> and <note> elements are placed before the selected text.

In the case of notes, however, it's common to insert them after the commented text.

I added new property position to the data passed to the function addAnnotation() that is defined in the pb-view-annotate.js web component,

The default value of the position property is around and can be changed by specifying the value after in the @class attribute of the button for the element, for example

<paper-icon-button class="annotation-action after" data-i18n="[title]annotations.note" title="Note" ...></paper-icon-button>

In the similar way, the value before in the @class attribute is used now for elements that should be placed after the selected text.

To be functional this change must be made at the same time as the change of the pb-view-annotate.js web component.

See parallel required pull request in the Web Components for TEI Publisher.