FS-9775: Some cleanup and bug fixes in DHT, switched to using hash destructors, and added sending of errors to most failed query scenarios

FS-9775: First tested pass on search functionality, not tested with deep searching at multiple levels

FS-9775: Bug fixes and exposed interface changes while implementing tests for get/put which are functional and pass initial tests now. Deep searching needs to be revamped now to complete the full announcing process.

FS-9775: Started working on "put", ran into a bug in job states which is fixed now, adjusted find_node response to add nodes to the job

FS-9775: Overhauled query/response handling by implementing a reusable job system to handle the common plumbing

FS-9775: Most of search functionality is finished, needs testing when route table is ready, still reviewing a few things related to recent lock changes

FS-9775: Major cleanup around allocations, more work on search functionality, adjusted polling to reduce timeout when outgoing messages are pending

FS-9775: Added initialization of threadpool, and switched parsing and processing of a received datagram to dispatch through the threadpool. Also a bit more work on searches sneaking in here.