Support "base" dataType

A new type has appeared in BH 10362082 (#1), which breaks the compatibility of the transaction v3 format.

{
    "version": "0x3",
    "timestamp": "0x5960a8b1a63dc",
    "dataType": "base",
    "data": {
        "prep": {
            "irep": "0xa968163f0a57b400000",
            "rrep": "0x2ac",
            "totalDelegation": "0x8caecae9866ca5730f6746",
            "value": "0x3fcd641964f21cea"
        },
        "result": {
            "coveredByFee": "0x1890f955b16000",
            "coveredByOverIssuedICX": "0x0",
            "issue": "0x3fb4d3200f40bcea"
        }
    },
    "txHash": "0xef839cb2d6e06b966f9ff5e0ca890c1d49737f4422b5ad87ae5a510a093ce35e"
}

Aegis v1.3 supports this new dataType.