Speedup 05: Retrieve unique detections in family and in matched_filter

[flixha]

What does this PR do?

• core.match_filter.family._uniq: 1.9x speedup
  • retrieving the unique list of detections is quicker for many detections with list(set) (1.9x speedup for 43000 detections, fastest: 3.1 s), but 1.2x slower for small sets (e.g., 430 detections; 50 ms --> 27 ms).
• core.match_filter.detect - 1000x speed up for many calls to family._uniq
  • using family._uniq in a loop over all families is still rather slow with _uniq. Checking tuples of (detection.id, detection.detect_time, detection.detect_val) with numpy.unique and avoiding a loop is 1000x faster. From 752 s to <1 s for 82000 detections.

Why was it initiated? Any relevant Issues?

Retrieving unique detections for matched_filter-run was getting slower than needed when there are a lot of detections.

This PR contributes to the summary issue in #522

PR Checklist

• develop base branch selected?
• This PR is not directly related to an existing issue (which has no PR yet).
• All tests still pass.
  - [ ] Any new features or fixed regressions are be covered via new tests.
  - [] Any new or changed features have are fully documented.
• Significant changes have been added to CHANGES.md.
  - [ ] First time contributors have added your name to CONTRIBUTORS.md.

[calum-chamberlain]

It looks like the changes to _uniq shouldn't work, and if they do then we should make sure they don't... Otherwise this is a really useful speedup!

[calum-chamberlain]

Golden, thanks!