Splitting Entry into Details.

- Preparing to turn Entry into the group class, and Details will
  become the per-line class.
- I'll be done with this damn refactor eventually.
Dreastic simplification of Entry and Details

- Existing API unchanged.
- Current tests unmodified to accomodate - they just work.
- This is what I've been driving for!
Further simplification of Details class.
No upper limit to number of log args!

- Long awaited feature.
- Logsaber#log now works very similar to `puts` and `print`,
  allowing multiple args and handling them in their own way.