2.11 fix

Fixed 

[error] /private/tmp/thyme/bench/Thyme.scala:1499: type mismatch;
[error]  found   : Any
[error]  required: Double
[error]     def done(dt: Double) = f"done in ${if (dt>=1) dt else dt*1e3}%.2f ${if (dt>=1) "s" else "ms"}\n"
[error]         

And 

error] /private/tmp/thyme/bench/Thyme.scala:84: in class Thyme, multiple overloaded alternatives of method porder define default arguments.
[error] class Thyme(val accuracyTarget: Double = 0.03, watchLoads: Boolean = true, watchGarbage: Boolean = true, watchMemory: Boolean = true) { self =>
[error]       ^
[error] one error found