repr does not allow reconstruction

[denizyuret]

Not sure if you would consider this an issue, but repr(Exponential(5)) does not give a string that can be parsed to get the same distribution: Exponential{Float64}(θ=19000.0). This makes simple serialization tricky. A simple fix would be to add a method such as: Exponential{T}(;θ::T) where T=Exponential(θ)