Hook Specification

[toddbaert]

We need to draft a specification for hooks. It must define things such as:

• basic hook concepts
• hook parameters, return values
• how hooks can be attached (globally on API singleton, on client, and on a particular flag evaluation)
• the order of hook execution
• the behavior of hooks with respect to error conditions and abnormal execution
• storing state within a hook
• whether or not it's appropriate for hooks to mutate and state on the hook context

And possibly more.

Scope

• [x] #40
• [x] #38
• [x] #68
• [x] #40
• [x] #48