Bug prevented lookup of Deeply::Nested::Class::Definitions.
Also properly differentiate when looking up docs/source for *commands* and for the class that represents the command, i.e:
show-doc show-source #=> displays show-source --help
show-doc Pry::Command::ShowSource #=> comments above class definition (as with any other class)
It's useful having Pry::WrappedModule and Pry::Method share as much interface as possible so that
methods can be indifferent to which one they get (a la show-source / edit)