Add computations::implemented_by.
Use a distinct feature to initialize value and reference computations.
Add the lazy computation.
Add the from_fusion_map computation.
Update mpl_extensions and refactor the feature_dependency_graph.
Make the traits SFINAE friendly.
Support CompositeFeatures in computation dependencies.
Rename implemented_by to alias.
Rename computations::value to computations::variable.
Add a `const` `result()` to `computations::typed`.
Reorder the template parameters of variable and reference computations.
Add computations::function.
Remove computations::from_fusion_map.
Huge rewrite using new design.
Add a unit test for `detail::update_computation`.
Make the update function static and add react::execute.
Swap execute and update; the new names fit better.
Make the retrieve function static.
Add random thoughts generated in the design process.
The default name of a computation is not the computation itself.

This is to trigger an error when a computation is used
when a name is expected.