As it was the case during the good old days when spacemacs was still a
baby, SPC h SPC now list correctly all the pre/init/post functions and
the associsted layer. It also now list properly the current owner of
a package so it is easy to find the owner of a package by narrowing
with `packagename owner`.
This new old functionality is possible by leveraging the last
improvements to the layer system (see previous commits).
TODO: update the sources for Ivy
Correctly augment the docstring based on the presence of b,f and /
bindings using dynamic hint.
b,f and / are not available if none of helm or ivy layers are used.
