Pairplots

[Diff since v2.7.0](https://github.com/sefffal/PairPlots.jl/compare/v2.7.0...v2.7.1)

[Diff since v2.6.1](https://github.com/sefffal/PairPlots.jl/compare/v2.6.1...v2.7.0)

features
Added new option for displaying correlations between each pair of variables

[Diff since v2.6.0](https://github.com/sefffal/PairPlots.jl/compare/v2.6.0...v2.6.1)

bug fixes

- fix alignment of bottom axis labels with last column (last column was not vertically aligned with the rest)

[Diff since v2.5.0](https://github.com/sefffal/PairPlots.jl/compare/v2.5.0...v2.6.0)

[Diff since v2.4.0](https://github.com/sefffal/PairPlots.jl/compare/v2.4.0...v2.5.0)

Improved default number of bins for histogram series and added a step-histogram behind the smoothed KDE along the diagonals.

[Diff since v2.3.1](https://github.com/sefffal/PairPlots.jl/compare/v2.3.1...v2.4.0)


**Merged pull requests:**
- Improve default formatter (38) (sefffal)