Replay subject

[triandco]

• Implemented a variant of a subject that "replays" old values to new subscribers by emitting them when they first subscribe
• Added two new test cases based on RxJs

[codecov-commenter]

Codecov Report

Merging #10 (0da9516) into main (cb7f745) will increase coverage by 3.03%. The diff coverage is 88.63%.

@@            Coverage Diff             @@
##             main      #10      +/-   ##
==========================================
+ Coverage   47.63%   50.67%   +3.03%     
==========================================
  Files          14       14              
  Lines        1100     1188      +88     
  Branches       44       46       +2     
==========================================
+ Hits          524      602      +78     
- Misses        564      572       +8     
- Partials       12       14       +2     

Flag	Coverage Δ
unittests	50.67% <88.63%> (+3.03%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
src/Subject.fs	88.75% <88.50%> (-0.30%)	:arrow_down:
src/AsyncObservable.fs	32.46% <100.00%> (+0.88%)	:arrow_up: