Summary: misc. EG changes and polishes (excluding 7013417)
Reviewed-by: twisti

Summary: Implement MH.asVarargsCollector, etc., and remove withTypeHandler.
Reviewed-by: twisti

Reviewed-by: xdono

Reviewed-by: twisti

Reviewed-by: twisti

Reviewed-by: twisti

Summary: Add JVM_CONSTANT_InvokeDynamic records to constant pool to determine per-instruction BSMs; add MethodHandleProvider.
Reviewed-by: twisti

Reviewed-by: darcy, weijun

Summary: split MethodHandle.invoke into invokeExact and invokeGeneric; also clean up JVM-to-Java interfaces
Reviewed-by: twisti

Summary: Fill in missing API implementations, fix numerous bugs, adjust APIs towards EG design.
Reviewed-by: twisti

Summary: JDK API and runtime (partial) for anonk, meth, indy
Reviewed-by: mr

4313887: New I/O: Improved filesystem interface
4607272: New I/O: Support asynchronous I/O
Reviewed-by: sherman, chegar