Support trait methods that return Result<Self, ...> and Option

Detects when trait methods return Result<Self, ...> or Option<Self> and expands the variant access with #call.map(Into::into). This takes advantage of the existing From/Into definitions for the Enum and its Variants.

The detection is robust to several variations for referring to these types:

• Result
• std::result::Result
• core::result::Result
• Option
• std::option::Option
• core::option::Option

Fixes #82