Replace await1[A].flatMap with receive1
Add process1.sliding which behaves like sliding on Scala collections
Merge pull request #221 from fthomas/sliding

Add process1.sliding, a well-behaved version of window
Merge pull request #220 from fthomas/receive1

Replace await1[A].flatMap with receive1?
Call tail only if necessary
Simplify process1.sliding
Remove some unnecessary type parameters
Merge branch 'master' into topic/subprocess