Rename or alias module#append_features to module#include_module
For Object#extend, the hook/callbacks methods are extend_object and extended.
For Module#include, the hook/callbacks methods are append_features and included.
The name append_features is a bit confusing / inconsistent.
What about renaming append_features to include_module (similar as extend_object for extend) ?
Alternatively, include_module could be defined as an alias to append_features (the latter could be made deprecated).