Wigners

[Diff since v1.1.0](https://github.com/Jutho/WignerSymbols.jl/compare/v1.1.0...v2.0.0)


**Closed issues:**
- optional arguments for non-global caching (12)

**Merged pull requests:**
- Install TagBot as a GitHub Action (11) (JuliaTagBot)

Switched to default return value RationalRoot{BigInt}, which is an exact representation (provided by RationalRoots.jl) that is converted to a floating point approximation depending on the context, using the AbstractIrrational infrastructure from Julia Base. Thanks to w-vdh for the PR that initiated this change.

[v1.0.0](https://github.com/Jutho/WignerSymbols.jl/tree/v1.0.0) (2019-07-08)

[Diff since v0.3.1](https://github.com/Jutho/WignerSymbols.jl/compare/v0.3.1...v1.0.0)

**Merged pull requests:**

- Switch to using HalfIntegers (6) ([Jutho](https://github.com/Jutho))

small change in conversion from `HalfInteger` to `AbstractFloat` and `Real`