add beta binomial distribution

[nignatiadis]

A short PR that implements the BetaBinomial distribution. This is needed for #226, but the PR should be self-contained.

I tried to follow the code for Binomial but am not sure about some things (especially rand having a separate signature withTuple{I,A}}) where {I<:Integer,A}).

[github-actions]

Package name	latest	stable
Mitosis.jl
Soss.jl

[codecov]

Codecov Report

Merging #234 (d9a0bf9) into master (6a42ef6) will increase coverage by 0.62%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #234      +/-   ##
==========================================
+ Coverage   44.60%   45.23%   +0.62%     
==========================================
  Files          42       43       +1     
  Lines        1307     1322      +15     
==========================================
+ Hits          583      598      +15     
  Misses        724      724              

Impacted Files	Coverage Δ
src/MeasureTheory.jl	50.00% <ø> (ø)
src/parameterized/betabinomial.jl	100.00% <100.00%> (ø)

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[github-actions]

Package name	latest	stable
Mitosis.jl
Soss.jl

[cscherrer]

Thanks @nignatiadis ! I pushed a commit running JuliaFormatter, and added a suggestion for rand. Unless there's an efficiency benefit to going through Distributions, this seems pretty clean to me. Let me know what you think :)

[github-actions]

Package name	latest	stable
Mitosis.jl
Soss.jl

[nignatiadis]

Thank you @cscherrer. Definitely makes sense to code it directly (and in fact, that's exactly the implementation in Distributions.jl).

[cscherrer]

Is there anything using proxy for this case? If nothing calls it let's leave it out until we need it. Then we need to bump the version and should be good to go

[nignatiadis]

Just removed proxy and bumped the version!

[github-actions]

Package name	latest	stable
Mitosis.jl
Soss.jl

[cscherrer]

Looks good! Thanks again @nignatiadis