Serve receipts by P2P

[AskAlexSharov]

Code is here: in getReceipts66 need uncomment things and inside AnswerGetReceiptsQuery implement re-execution of requested blocks - to produce Receipts.

Additional: need use only 1 gorotine for all such P2P requests. (probably by *semaphore.Weighted)

Additional: add LRU of results.

Example of block re-exec see in: getLogsV3. (there is use of intraBlockExec).
See also Receipts LRU in RPCDaemon (as an example. don't re-use it).

[Giulio2002]

My 2 cents: this should be priority low and probably be not a "requirement" for E3 alpha

[AskAlexSharov]

agree. created beta milestone. moved issue there.