Feature warning errors for usage of postfix method calls, like in
```scala
10 milliseconds
// As opposed to
10.milliseconds
```

From [Scaladoc](http://www.scala-lang.org/api/current/index.html#scala.language$)
> Only where enabled, postfix operator notation (expr op) will be allowed.
> Why keep the feature? Several DSLs written in Scala need the notation.
> Why control it? Postfix operators interact poorly with semicolon inference. Most programmers avoid them for this reason.

From [Scala style guide](http://docs.scala-lang.org/style/method-invocation.html#suffix_notation)
> This style is unsafe, and should not be used. Since semicolons are optional, the compiler will attempt to treat it as an infix method if it can, potentially taking a term from the next line.
> This may result in unexpected compile errors at best, and happily compiled faulty code at worst. Although the syntax is used by some DSLs, it should be considered deprecated, and avoided.
> As of Scala 2.10, using suffix operator notation will result in a compiler warning.

I've left the remaining code (for now) since it looks great and is often seen for durations (as a DSL), but we should decide what should we do.

Sorry for the verbose response :wink: