- Added documentation and renamed some constants.
- Turned on the acts tracking geometry.

Paying attention to following items:
* Overall parameterization -- will use for optimization
* Constant naming consistency
* Documentation via the comments
* Added new ci job which concatenates all the `<comment>` tags into `docs/detector.md`
* All comments should now be formatted to fit the appropriate section in the markdown file.

- Todo: merge the repeated ids into a single detector construction if
  possible

	modified:   compact/definitions.xml

This allows for a frame to be defined as the subtraction of 2 trds.