Valid8

* Fixed [23](https://github.com/smarie/python-valid8/issues/23)

* Fixed [22](https://github.com/smarie/python-valid8/issues/22)

* Fixed typos detection: [21](https://github.com/smarie/python-valid8/issues/21)
* Fixed np.nan handling: [20](https://github.com/smarie/python-valid8/issues/20)

* values with string representation larger than 100 characters are not anymore displayed in the error messages by default. Fixes [19](https://github.com/smarie/python-valid8/issues/19)
* new class method `ValidationError.create_manually` to create validation errors manually in some edge cases, without a validator entry point

* Fixes [18](https://github.com/smarie/python-valid8/issues/18)

* The init file has been improved so as not to export symbols from other packages. Fixes [15](https://github.com/smarie/python-valid8/issues/15)