Pyxirr

- Remove pyo3 wrappers from core
- Benchmark: compare with `numpy-financial`

- MIRR, FV
- Performance improvements ([6](https://github.com/Anexen/pyxirr/pull/6))
- Test without numpy
- Setup Github Action for benchmark ([5](https://github.com/Anexen/pyxirr/pull/5))

- Add FV

- Add IRR & NPV ([4](https://github.com/Anexen/pyxirr/pull/4))
- Optimize cargo build profile for speed
- Setup Github actions for testing and publishing

- Faster conversion from `numpy` arrays ([3](https://github.com/Anexen/pyxirr/pull/3))

- Simplify python conversions
- Refactor tests
- Numpy & Pandas support ([2](https://github.com/Anexen/pyxirr/pull/2))