add events to reactionsystem by wrapping them in a constraintsystem

[paulflang]

No description provided.

[codecov]

Codecov Report

Merging #82 (c1c470e) into main (ff5c09b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #82   +/-   ##
=======================================
  Coverage   98.70%   98.70%           
=======================================
  Files           1        1           
  Lines         231      231           
=======================================
  Hits          228      228           
  Misses          3        3           

Impacted Files	Coverage Δ
src/reactionsystem.jl	98.70% <100.00%> (ø)

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[isaacsas]

Looks good to me. You could add an example that actually uses an event and checks the ODE solution does what it should if you want to be a bit more thorough about the event actually running correctly.