Conflict with Webform Rules: Re-namespace Webform Tokens tokens

A while ago, I tried to get Webform Rules to resolve the conflicting use of the webform token namespace. We were making some progress, but then Webform 4 came out, the token formats changed, and so on, and it never happened.

I want to resolve this incompatibility, once and for all, so I am changing Webform Tokens' token namespace to webform-tokens.

This is only a breaking change when Webform Rules is enabled, and there is a note about this on the project page. That's why it's not in a new branch.

We will be integrating with Webform's own token type soon, anyway, so this didn't merit a new version. The 7.x-2.x branch will contain the behavior switch, since that by any stretch will be a breaking change.

What this means: If you use [webform:] tokens right now that Webform Tokens provides, and you use Webform Rules, you must switch to [webform-tokens:].

If you don't use Webform Rules, you shouldn't notice anything. You should try to stick to [webform-tokens:] tokens from now on, though.