Lib.rs

Splits the Rust number API into common traits, with a cleaner design than num.

The base num trait represents data-types that represent abstract numbers, with the usual +-*/% operators. So no measurement units (Meters) or operator blocking (Position).

A Num can't nessesarely represent any specific value (0, 1, 2...), because a number type might, for example, represent only numbers in the range of 100...356.

Number APIs are each in a different trait and can be also implemented by non numbers. For example: a Vec2 can't implement Num but it can implement Round.