interpret relative directions inside location interpreter

## Type of Issue

Select the type of issue:
- [ ] Bug report (to report a bug)
- [ ] Feature request (to request an additional feature)
- [ ] Tracker (I am just using this as a tracker)
- [x] Refactor request
- [ ] Documentation Ask

## Description

relative directions are interpreted by interpret_relative_directions, outside of location interpreter (in main interpreter); and then the results passed to the subinterpret["specify_locations"]. refactor so that the location interpreter does all of this.