Feature - In-core report script execution

Description

Right now report scripts are executed in MongoDB. While this allows for database accesses which could be useful, it is also very, very slow, and deprecated to boot. Instead we could use something like J2V8.

Priority

High - if it ain't broke, don't fix it Well it broke the core, so it's time to fix it.

Definition of done

When the user can choose between MongoDB (for the query options) and the more efficient J2V8 runtime.