WIP: Breaking changes

Many breaking changes:

• Use a less biometric-related name for functions (setup aliases)
• Reduce package-namespace cluttering by moving elements to submodules
• Improve confidence interval and add credible region analysis support, documentation, plotting support and paired system comparison. Limited testing is available for the time being
• Reduce to a bare minimal the amount of stuff that needs to numba-fied. Everything else can be just proper Python code.
• Pin matplotlib to 3.4.x to avoid issues with multi-page PDF output with 3.5.0