imbue builders and readers with cap tables

[vaci]

In order to implement the RPC features of Capnproto in Java, the most intrusive change to the existing codebase is to imbue builders and readers with the tables for tracking references to any capabilities that may be associated with an arena.

This patch does the trivial but tedious work of wiring capability tables into builders and readers. Backward compatibility is maintained in existing method signatures by defaulting the optional capTable parameter to null.

[mikehearn]

Is there a reason this was never reviewed? Is the intention to never add RPC support to the Java implementation?