Separate renderer into their own classes

[froemken]

This is just a first step to a much cleaner code. I have separated the renderer into their own classes, tagged them as service and inject them as interable. Here the specific renderer will be automatically detected and used to render the specific codesnippet configuration entry.

I have changed nearly no other code. OK, I have removed an empty line here and there or add an empty line for better visibility. Further I have returned a value directly instead of assigning result into a variable first and then returning it.