tailrec and addressed comments

[info] a.a.ActorPathValidationBenchmark.handHarder    thrpt        10
100.167        2.458   ops/ms
[info] a.a.ActorPathValidationBenchmark.handLoop      thrpt        10
31.564        1.172   ops/ms
[info] a.a.ActorPathValidationBenchmark.old           thrpt        10
2.898        0.163   ops/ms