wip for partial write flushes. Design still in flux, won't appear on master until it makes sense.
Whoops.
Reusing IDataStoreWriter across multiple commit() calls. Lots of ramifications, but flushing writes at 64k now works (kinda)
AckWriteAction. Currently simply triggers drop behavior on ack when appropriate.
Quick little comment.
Making write callbacks persist state across calls w/ the same WriteParams. (filename, version, etc)
 * primarily changes to WriteActionSender and MirrorToPeer
 * new flag in WriteParams for WriteActionSender's usage: "isComplete". Designates last packet of write.
Refactoring common MirrorToPeer logic into ChainWrite class for easier testing.