Use Scala Macros to avoid the stateful Source/Sink creation

0.5.0

merge macros into master

Bugfixes and improvements

• Use MergeHub and BroadcastHub to avoid preMaterialize's closing problem.
• Use SourceQueue and SinkQueue to force typing.

Bump Akka version and remove custom zipLatest

0.4.2

bump the akka version and remove custom zipLatest

Separate the implicit classes for Source and Flow

Since F[O, M] cannot recognize Flow properly, write another implicit class for Flow before better solution is found.