Create unified Traits that can be used for any formatting library

[vitiral]

This is in reference to the discussion in #3 concerning using a Format Trait to be able to format any type.

• Ideally this would use Implement RFC 1210: impl specialization rust-lang/rust#30652 to be able to also fallback to the standard Display type.
• however, Display uses the fmt::Formatter struct, instead of using a trait. This makes this almost impossible to implement.

Suggested action is:

• make Formatter a trait instead of a struct in the rust stdlib
• implement the trait