Feature/x3 keywords

This pull request adds the keyword parser to the extensions. This only covers the case sensitive version. 
Should case insensitive behavior be necessary I can extend this in the future.

I consider this version of the keywords parser as suitable to be merged into develop.
Should something be wrong, or missing, or to be improved please let me know.

1. and 2. Yes of course. 
3. I'll look into that.