Search panel added to make easier to find snippets 

Hi,

We were using this in a production greatvenue.com and we find the text we want amongst 50 or more snippets. Therefore I added a search for it.
The idea is that the person who is updating the snippets doesn't know where they are in the templates so he can't look up. He tried categorizing them but it is still painfull to keep in mind which key what covers in the ui. Even myself forget those keys. So I added a search for the snippets.