Review use of pub type = Foo; and the quality of the resulting documentation

[mitchmindtree]

Unfortunately after all these years rustdoc still does support type aliases very well. In code, type aliases are really useful for filing in some generic type parameters and simplifying the resulting type. However, the resulting documentation does not present the impls for these type aliases, and only points to the (often vastly more complicated) generic type documentation. Some key examples in nannou are the Drawing* types and the Text iterator return types (e.g. Glyphs).

Perhaps it's worth reviewing the use of all the cases where we use pub type = and seeing if we can use struct wrapper types on which we can provide better docs? This isn't possible in the case of the Drawing type, but might be possible elsewhere.

Alternatively it might be worth trying to fix rustdoc itself - see the linked issues below.

Related issues:

• rustdoc doesn't substitute type parameters rust-lang/rust#14072
• Rustdoc doesn't handle impl section of type definitions rust-lang/rust#32077
• Improve documentation for draw.line(), draw.eclipse()`, etc methods #252