SPECS2-4.6.0

This version is compatible with both Scala 2.13 should be compatible with Dotty except for features using macros.

Improvements

• run on Scala 2.13 thanks to @SethTisue, @rossabaker

Fixes

• #751 fix for implicit resolution on Dotty thanks to @smarter
• #748 fixed a stack overflow with Producer.emitSeq (could happen with large specifications)
• #747 rethrow failures with a not matcher in mutable specs
• fixed a comment on SimpleTimer and added a return type
• fixed one edge case with implicit resolution on Scala 2.13: beSome(beLeft) (reported by @xuwei-k)