Refractiveindex

[Diff since v0.4.2](https://github.com/stillyslalom/RefractiveIndex.jl/compare/v0.4.2...v0.4.3)

[Diff since v0.4.1](https://github.com/stillyslalom/RefractiveIndex.jl/compare/v0.4.1...v0.4.2)



**Closed issues:**
- Calculate refractive index from a formula (18)

[Diff since v0.4.0](https://github.com/stillyslalom/RefractiveIndex.jl/compare/v0.4.0...v0.4.1)

[Diff since v0.3.1](https://github.com/stillyslalom/RefractiveIndex.jl/compare/v0.3.1...v0.4.0)


**Merged pull requests:**
- Migrate from SnoopPrecompile to PrecompileTools (17) (timholy)

[Diff since v0.3.0](https://github.com/stillyslalom/RefractiveIndex.jl/compare/v0.3.0...v0.3.1)


**Closed issues:**
- Handle database entries with multiple dispersion data (14)

[Diff since v0.2.1](https://github.com/stillyslalom/RefractiveIndex.jl/compare/v0.2.1...v0.3.0)