On: Stop avoiding regular expressions damn it

[rcfox]

Just curious: how do the regexes compare when you use "^@(.*)@$" ? Semantically, it's closer to the string version.

Realistically, you'd expect them to behave exactly the same, but Go's pretty new, and you never know what is or isn't going to be optimized.

[Titanous → rcfox]

    `\A@(.*)@\z`

    BenchmarkRegexp	  500000	      5181 ns/op
    BenchmarkStrings	10000000	       171 ns/op