include 2.11 into the regular build
Setting version to 7.1.0-M4
Setting version to 7.1.0-SNAPSHOT
s/7.0.4/7.0.5
UnwriterT Bind law test
add FutureInstances to AllInstances
optimize groupWhen
groupWhen test
simplified type lambda
mapAccumLeft and mapAccumRight test
optimize mapAccumLeft and mapAccumRight. avoid stack overflow
Adhere to (or circumvent) stricter 2.11 variance checks

Focus is to get things compiling again. The places with
`@uncheckedVariance` might need review/deprecation.

Good old Liskov features heavily.

(forward-port of 8ddb8d31b3fbdf9bf0e715da94f1a2124e982afd)
Further variance problems in 2.11.0-M8.
Adhere to stricter 2.11 variance checks. (#598)
remove unused imports
tailrec annotation
remove unnecessary type parameter
DList head/tail -> headOption/tailOption
restored/deprecated existing head/tail; fixed test idiocy
fixed version (duh)