router: full on refactor

[yoshuawuyts]

Whoop whoop, full on refactor! Been playing with this for idk how long. Mostly cleaned up internals so other routers can be built on top of this without having to worry about how to do composition (check out require('trie').mount() ✨). whoop!

Closes #32 #33 #34

Changed

• removed multiplexed events
• removed symbols dependency
• removed internal method exposure; the need for that was an indication of
  lower level problems that this patch fixes

Added

• matched routes can now return values (useful for streams)
• Trie data structure can now be required doing require('wayfarer/trie')

Fixed

• moved to using a single trie which greatly decreases lookup times
• moved lookup logic to separate (internal) data structure which improves perf

Known issues

• mounting multiple partial routes as direct children will error

[yoshuawuyts]

Welp, no objections so far. I've seen some people ACK that they've seen it on twitter, so unless anyone has strong objections I'll merge it tomorrow morning (in like 8 hours) ✨

[yoshuawuyts]

Just realized there's a bug in the resolution algorithm that's not being checked for; /foo and /:user currently cannot co-exist on the same router, therefor regular paths must be searched before named paths. This will require additional tests to be added / a tweak to the trie.search() function.

[yoshuawuyts]

Annnd it's fixed! Publishing new version once tests pass.