Configuration Changes

• The original tx_pool_min_tx_gas_price is separated to two configurations tx_pool_min_native_tx_gas_price and tx_pool_min_eth_tx_gas_price for two spaces.
• The default tx_pool_size is changed to 50000 to avoid possible OOM because of large transactions.

RPC Changes

• Support EIP-1898 style epoch parameters in some core space RPCs (including cfx_getBalance, cfx_getStorageAt, cfx_call, cfx_getNextNonce, cfx_getCode, and cfx_epochReceipts). Check #2615 for details.
• Add filter RPCs for cfx core space (including cfx_newFilter, cfx_newBlockFilter, cfx_newPendingTransactionFilter, cfx_getFilterChanges, cfx_getFilterLogs, and cfx_uninstallFilter).
• Add pos_getAccountByPowAddress to query the PoS account information in one RPC call.
• Add two more pending reasons (oldEpochHeight and outdatedStatus) for firstTxStatus returned in cfx_getAccountPendingTransactions. Check #2624 for defails.

Improvements

• Allow the node database snapshot from Linux to be used by a Windows executable.

Bug Fixes

• Limit the chunk size when loading from db in syncing snapshot to avoid OOM.
• Fix an issue that a light client might be deadlocked.
• Allow nodes to disconnect not-responding light nodes.