Memos for RVN transactions

[TronBlack]

RPC calls that add memos for RVN transactions.

Extensions of:

sendfrom "fromaccount" "toaddress" amount ( minconf "comment" "comment_to" )
sendfromaddress "from_address" "to_address" amount ( "comment" "comment_to" subtractfeefromamount replaceable conf_target "estimate_mode")
sendtoaddress "address" amount ( "comment" "comment_to" subtractfeefromamount replaceable conf_target "estimate_mode")

sendfromwithmemo "fromaccount" "toaddress" amount **memo** ( minconf "comment" "comment_to" )
sendfromaddresswithmemo "from_address" "to_address" amount **memo** ( "comment" "comment_to" subtractfeefromamount replaceable conf_target "estimate_mode")
sendtoaddresswithmemo "address" amount **memo** ( "comment" "comment_to" subtractfeefromamount replaceable conf_target "estimate_mode")

memo is either IPFS content ID, or 64 character hex string (32 bytes)

Use the same encoding for IPFS or OIP hash. 0x12 0x20 <32 bytes>

The memo goes in the OP_RETURN and does require a hard fork.

The database should include these memos and be queryable via RPC calls and work the same as the IPFS or OIP for Assets. The same encoding, decoding, and RPC reporting.