v0.5.0

v0.5.0 - Require consumer to opt in to use autowiring

The approach of "autowire all the things" entailed awkward semantics
for `ContainerInterface::has()` implementation, and awkward
implementation involving catching `\ReflectionException` etc.

Requiring specific opt-in for autowiring a class results in a cleaner,
more performant implementation and more obvious semantics for `::has()`.