Add full paths to org.parboiled2 types in qqotes

When building up parsers, often it may not be necessary to import the entire org.parboiled2 package. However, many of the names used in quasiquotes in the OpTreeContext trait currently rely on that path being available to resolve things like Parser and Rule, and will fail with the usual lack of information if they are not imported. 
### This pull request adds:
* The whole path to the relevant quasiquotes
* A test which demonstrates the behavior