DRAFT: Feature: compatibility with drawille-rs crate

[VincentFoulon80]

When merged, this branch will add two new features :

• compatibility : this feature will expose a trait AsScreen that'll allow anybody to implement a method to convert its object to a Screen, allowing compatibility with external crates and custom structures
• compatibility-drawille : This feature will bridge a compatibility layer between console_engine and drawille-rs.

The new AsScreen trait can also be used for direct drawing of any compatible structure with two new methods print_with and print_alpha_with.

[VincentFoulon80]

I'll postpone this PR a bit, since the drawille crate got a new maintainer, I think this need a bit more time to decide how to link these crates together properly.