Evaluate a new way to compare handlers.

(From Slack conversation about #242.)

The comparison function to identify equivalency relies on everything coming in at the same time. We should consider a different approach that allows for piece-wise comparison and setting of things like context.

@rwjblue "proposed" `setContext` as a method, and `matchesContext` to be part of the evaluation function for equivalency.

Something like this would make it a bit easier to split the responsibilities of checking handler identity into manageable bites.

Start by locating the comparison function used to identify handler equivalency and review the discussion linked from #242. Determine how piece-wise comparison and context handling would fit the proposed setContext and matchesContext responsibilities. Done means the project has a decided approach for splitting handler identity checks, with its equivalency behavior clearly defined.

Written by the indexing model from the issue text.