Support HTML as content for the name of an item

[bbrala]

As discussed in #252 a way to add HTML as an item that plays nicely with the different item types.

[arai-a]

there could be 2 ways to solve it:

1. Different property for HTML
   If item.html property exists, call .html(item.html) instead of .text(item.name)
2. Flag property to mark it as HTML
   If item.isHTML property is true, call .html(item.name) instead of .text(item.name)

in both way, property name is just a draft, there could be better name.

The problem is that there is already item.type == 'html' with item.html property for content. It should be nice to make these 2 types clearly distinguishable.

[brassard]

Proposed a PR #388 to address this issue.

[brassard]

I believe that this issue is resolved with the now-merged PR #388.

[bbrala]

Yes! :) I went through the issues, but didnt go back enough. Thanks