add option to calc emission delay

[mdoucet]

Add option to compute emission delay instead of using effective distance.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 69.84127% with 19 lines in your changes missing coverage. Please review.

Project coverage is 82.16%. Comparing base (f7d3627) to head (5097619).
Report is 8 commits behind head on next.

Files with missing lines	Patch %	Lines
reduction/lr_reduction/event_reduction.py	66.66%	12 Missing ⚠️
reduction/lr_reduction/template.py	46.15%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             next      #43      +/-   ##
==========================================
- Coverage   82.20%   82.16%   -0.05%     
==========================================
  Files          20       20              
  Lines        2327     2394      +67     
==========================================
+ Hits         1913     1967      +54     
- Misses        414      427      +13     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[backmari]

Looks good to me