Refactor to remove various warnings

[jardinetsouffleton]

 Warning: `dropgrad(x)` is deprecated, use `ChainRulesCore.ignore_derivatives(x)` instead.
│   caller = adjoint at deprecated.jl:13 [inlined]
└ @ Core ~/.julia/packages/Zygote/AS0Go/src/deprecated.jl:13
┌ Warning: `ignore(f)` is deprecated, use `ChainRulesCore.ignore_derivatives(f)` instead.
│   caller = adjoint at deprecated.jl:31 [inlined]
└ @ Core ~/.julia/packages/Zygote/AS0Go/src/deprecated.jl:31
┌ Warning: keyword initW is deprecated, please use init (which similarly accepts a funtion like randn)
│   caller = ip:0x0
└ @ Core :-1
┌ Warning: `dropgrad(x)` is deprecated, use `ChainRulesCore.ignore_derivatives(x)` instead.
│   caller = adjoint at deprecated.jl:13 [inlined]
└ @ Core ~/.julia/packages/Zygote/AS0Go/src/deprecated.jl:13
┌ Warning: `ignore(f)` is deprecated, use `ChainRulesCore.ignore_derivatives(f)` instead.
│   caller = adjoint at deprecated.jl:31 [inlined]
└ @ Core ~/.julia/packages/Zygote/AS0Go/src/deprecated.jl:31
┌ Warning: `Truncated(d::UnivariateDistribution, l::Real, u::Real)` is deprecated, use `truncated(d, l, u)` instead.
│   caller = ip:0x0
└ @ Core :-1