feat: add option to display TextMate token info in hover

[sebthom]

This PR adds the ability to show the type and scopes of TextMate tokens in a hover which is useful when developing TM themes and needing to style specific elements.

[angelozerr]

It is a fantastic feature! Please note that vscode provides this features too https://code.visualstudio.com/api/language-extensions/syntax-highlight-guide#textmate-tokens-and-scopes andit display another relevant information

And vscode manage this popup with the cursor, if you change the cursor the popup is refreshed,I think it is better than hover but I don't know if it is easy to do that in Eclipse IDE.

[sebthom]

@angelozerr We currently don't have all this information available. However, I added a second commit that extends the hover like this:

[angelozerr]

Thanks @sebthom for your improvement.

I suggest that you write a doc about this great feature