Added functions to cache and manage yield calculations

Removed "tx.amount_locked" field - "tx.amount_burnt" is technically correct for all cases.
Removed invalid checkpoint data.

src/cryptonote_core/blockchain.h

@@ -746,6 +746,8 @@ namespace cryptonote
      */
     uint64_t get_current_cumulative_block_weight_median() const;
 
+    int get_yield_info(const uint64_t start_height, const uint64_t end_height, std::vector<std::pair<yield_tx_info, uint64_t>>& yield_container);
+    
     /**
      * @brief gets the difficulty of the block with a given height
      *
@@ -1145,6 +1147,33 @@ namespace cryptonote
      */
     uint64_t get_adjusted_time(uint64_t height) const;
 
+    /**
+     * calculate the yield payouts
+     *
+     * @return TRUE if the payouts were calculated successfully, FALSE otherwise
+     */
+    bool calculate_yield_payouts(const uint64_t start_height, std::vector<std::pair<yield_tx_info, uint64_t>>& yield_payouts);
+    
+    /**
+     * (re)build the yield_block_info cache from the blockchain
+     *
+     * @return TRUE if the cache rebuilt correctly, FALSE otherwise
+     */
+    bool rebuild_ybi_cache();
+    
+    /**
+     * @brief validate the yield_block_info cache
+     *
+     * Checks that the m_yield_block_info_cache is fully populated by
+     * checking the size of the map, and making sure it has the most recent entry
+     * and the oldest expected entry as well
+     *
+     * Returns TRUE if the cache is intact, full, and up-to-date, FALSE otherwise
+     *
+     * @return TRUE if cache is OK, FALSE otherwise
+     */
+    bool validate_ybi_cache();
+
 #ifndef IN_UNIT_TESTS
   private:
 #endif
@@ -1250,6 +1279,8 @@ namespace cryptonote
     // cache for verifying transaction RCT non semantics
     mutable rct_ver_cache_t m_rct_ver_cache;
 
+    std::map<uint64_t, yield_block_info> m_yield_block_info_cache;
+    
     /**
      * @brief collects the keys for all outputs being "spent" as an input
      *