Update to JDK 8

[JosephCottam]

Default method implementations handy for many interfaces...
Lambda might make "Valuer" obsolete...
Stream interface for implicitGeometry....
ForkJoinPool.commonPool()...
For/Join accumulators for aggregation...
Optional for managing nulls...

[JosephCottam]

Started to work on this with commit f25a697

[JosephCottam]

Valuer and shaper are now use lambdas and places using them now use Function.