Enforce restricted # pool txs served via RPC + optimize chunked reqs [release-v0.18]

- `/getblocks.bin` respects the `RESTRICTED_TX_COUNT` (=100) when
returning pool txs via a restricted RPC daemon.
- A restricted RPC daemon includes a max of `RESTRICTED_TX_COUNT` txs
in the `added_pool_txs` field, and returns any remaining pool hashes
in the `remaining_added_pool_txids` field. The client then requests
the remaining txs via `/gettransactions` in chunks.
- `/gettransactions` no longer does expensive no-ops for ALL pool txs
if the client requests a subset of pool txs. Instead it searches for
the txs the client explicitly requests.
- Reset `m_pool_info_query_time` when a user:
  (1) rescans the chain (so the wallet re-requests the whole pool)
  (2) changes the daemon their wallets points to (a new daemon would
      have a different view of the pool)
- `/getblocks.bin` respects the `req.prune` field when returning
pool txs.
- Pool extension fields in response to `/getblocks.bin` are optional
with default 0'd values.

src/wallet/wallet_rpc_server.cpp

@@ -149,8 +149,10 @@ namespace tools
         return true;
       if (boost::posix_time::microsec_clock::universal_time() < m_last_auto_refresh_time + boost::posix_time::seconds(m_auto_refresh_period))
         return true;
+      uint64_t blocks_fetched = 0;
       try {
-        if (m_wallet) m_wallet->refresh(m_wallet->is_trusted_daemon());
+        bool received_money = false;
+        if (m_wallet) m_wallet->refresh(m_wallet->is_trusted_daemon(), 0, blocks_fetched, received_money, true, true);
       } catch (const std::exception& ex) {
         LOG_ERROR("Exception at while refreshing, what=" << ex.what());
       }