json serialization for rpc-relevant monero types

Structured {de-,}serialization methods for (many new) types
which are used for requests or responses in the RPC.

New types include RPC requests and responses, and structs which compose
types within those.

# Conflicts:
#	src/cryptonote_core/blockchain.cpp

src/cryptonote_core/cryptonote_core.cpp

@@ -790,6 +790,13 @@ namespace cryptonote
     return BLOCKS_SYNCHRONIZING_DEFAULT_COUNT_PRE_V4;
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::are_key_images_spent_in_pool(const std::vector<crypto::key_image>& key_im, std::vector<bool> &spent) const
+  {
+    spent.clear();
+
+    return m_mempool.check_for_key_images(key_im, spent);
+  }
+  //-----------------------------------------------------------------------------------------------
   std::pair<uint64_t, uint64_t> core::get_coinbase_tx_sum(const uint64_t start_offset, const size_t count)
   {
     uint64_t emission_amount = 0;
@@ -1175,6 +1182,11 @@ namespace cryptonote
     return m_mempool.get_transactions_and_spent_keys_info(tx_infos, key_image_infos);
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::get_pool_for_rpc(std::vector<cryptonote::rpc::tx_in_pool>& tx_infos, cryptonote::rpc::key_images_with_tx_hashes& key_image_infos) const
+  {
+    return m_mempool.get_pool_for_rpc(tx_infos, key_image_infos);
+  }
+  //-----------------------------------------------------------------------------------------------
   bool core::get_short_chain_history(std::list<crypto::hash>& ids) const
   {
     return m_blockchain_storage.get_short_chain_history(ids);