add missing header end comments

- ensures a consistent usage in header files
- also add a blank line after the copyright header where missing
- also remove orphan new-lines at the end of some files

src/core_write.cpp

@@ -89,4 +89,3 @@ void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry)
     if (hashBlock != 0)
         entry.pushKV("blockhash", hashBlock.GetHex());
 }
-