refactor command routing similar to http.ServeMux

[Jon]

Provides better maintainability, testability, and lays the foundation for easier plugin support.

• benchmark perf tradeoffs between regex and string matches
• investigate abstracting commands as command.CommandFunc

[Jon]

Initial impl ubenchmarks

C:\Users\Jon\Documents\GoDev\mygo\src\bitbucket.org\jonforums\uru>go test -run NONE -bench=.
PASS
BenchmarkRegexCompare   20000000               104 ns/op
BenchmarkStringCompare  2000000000               0.30 ns/op
BenchmarkMultiStringCompare     2000000000               0.30 ns/op
BenchmarkSwitchRouter     500000              3865 ns/op
BenchmarkCommandRouter   1000000              1212 ns/op

[Jon]

Refactor command routing internals. Closes #65

Simpler, more performant, and more extensible command routing. Replace switch-and-regex based routing with string comparing, function pointer based CommandRouter component.

Initial impl micro-benchmark results:

BenchmarkSwitchRouter 500000 3865 ns/op BenchmarkCommandRouter 1000000 1212 ns/op

→ <<cset 6df3c4d6ed7c>>