Layout runtime interfaces

[Tobi Ajila]

We have a created a prototype of Java layouts which can be found here,
https://github.com/J9Java/panama-layout-prototype. The purpose of this
prototype is to demonstrate the major features of the Layout Runtime and to
advance the design discussions. The prototype is work in progress and more
updates will be made as the design issues are resolved. We invite others to
participate and further the development of Layouts; by contributing to the
project. Documentation outlining the design and usage of the prototype can
be found here, https://github.com/J9Java/panama-docs, we can use it as a
starting point for discussion. We have also moved the LDL documentation to
the same repo.

Regards,
--Tobi