Catchain improvements (#698)

* Fix "sgn" in fift; fix marking infinite loops as noterurn in func

* TON-P1-1: Remove unused catchain queries

* TON-P1-15: Avoid synchronization with self

* TON-P1-3, TON-P1-17: Disallow more than one candidate per src per round (to prevent flood), add checks to process_broadcast

* TON-P1-10: Fix fast/slow attempts

* TON-P1-14: Add named constants

* TON-P1-18, TON-P1-19: Alloc temporary memory in the same way as persistent memory

* TON-P1-20: Add comment to choose_blocks_to_approve

* TON-P1-16: Avoid creating two catchain blocks on need_new_block

* TON-P1-8: Add some validation to validator-engine parameters

* TON-P1-6: Don't allow sending the same block many times

Many requests for the same block are not unusual (however, there's no need to answer them all)

* TON-P1-2: Enable prohibiting dependencies from blamed nodes (2.7.5 in CatChain doc), fix processing blame proofs

* Best practices

bp-6: Fix incorrect warning
bp-7: Remove unused code
bp-8: Bring back PerfWarningTimer logging (only when no callback)
bp-9: Remove unnecessary condition
bp-11: Remove commented-out code
bp-13: Divide code in validator-session-state
Adherence to Specification: Fix typo

catchain/catchain-receiver-source.h

@@ -61,6 +61,9 @@ class CatChainReceiverSource {
   virtual td::BufferSlice fork_proof() const = 0;
   virtual bool fork_is_found() const = 0;
 
+  // One block can be sent to one node only a limited number of times to prevent DoS
+  virtual bool allow_send_block(CatChainBlockHash hash) = 0;
+
   static td::Result<std::unique_ptr<CatChainReceiverSource>> create(CatChainReceiver *chain, PublicKey pub_key,
                                                                     adnl::AdnlNodeIdShort adnl_id, td::uint32 id);