Add strip_tags()

[web64]

First of all, thanks for a great library!

A strip_tags() function that actually works would be a great addition! Must be able to handle:

• prevent words from being joined when tags are removed: example: word<br />another_word

Here is what I'm using at the moment: https://gist.github.com/web64/b0efa3f001401950f26fb72f5eff8674