The hooks were executed in the same order regarding of if they were pre
or post hooks.
This is actually not a correct behavior, let's assume we want to create
a hook responsible for keeping the position of the cursor between
operations:
The pre hook will have to extract the current position of the cursor and
therefore should be the first one to be executed, let's say we gave it a
priority 0.
The post hook will have to reposition the cursor after the
transformation and therefore should be the last one to be executed.
That's why we need to reverse the order of the post hooks.
It is still not possible to override an existing hook but with this
system users can create new hooks really simply without having to update
any configuration since they will be autodetected.
The only missing thins is the possibility to disable hook, therefore it
is the responsibility of each hook to provide a way to the user to use
it or not.
