New helper functions

This release adds helper functions made by @tadeubarbosa

• percentage()
• percentage_between()
• percentage_abs_between()
• percentage_of()
• percentage_extension()

Add support for PHP 8

Add support for PHP 8

Explicit input types

Be more explicit about the function arguments, they should all be casted to floats.

First stable release

Time to tag the first stable release, this is working as intended and saves me a lot of mental energy when writing code! 🥳

New method names for clarity (beta)

Merge pull request #2 from ianrodrigues/patch-2

Clean up

alpha release

0.2

wip

First release, very beta

0.1

wip