Provide more RPC help information + sendrawtx_MP: add reference amount

sendrawtx_MP can now be used with a reference amount. Behavior as expected:

```
mastercore-cli sendrawtx_MP "mvayzbj425X55kRLLPQiuCXWUED6LMP65C" "000000000000000200000000004c4b40" "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ" "" "0.123"
bb495d9d927b12180dc7f298d36219bf23954890aa976df8868203fcaf947d19

mastercore-cli sendrawtx_MP "mvayzbj425X55kRLLPQiuCXWUED6LMP65C" "000000000000000200000000000001f4" "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ"
9e93d5d2b8391fd6f1cea8f367bd628a4a5ca828fdec68ee4ffa234787e42c5e

mastercore-cli send_MP "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ" "mvayzbj425X55kRLLPQiuCXWUED6LMP65C" 1 "0.005" "" "0.00321"
a8e6abec9706909523a3e41f2bf61cf4261542a1e57b4fcf16f28d671e3ecff8

mastercore-cli send_MP "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ" "mvayzbj425X55kRLLPQiuCXWUED6LMP65C" 2 "0.002"
0898388becece2a37233acffe605786ab43df8d185d54c68b13be20324414759

mastercore-cli sendrawtx_MP "mvayzbj425X55kRLLPQiuCXWUED6LMP65C" "0000000000000001000000000007a120" "n4EmA9R4VmxLnxu9G8yZMDxvBBha8bUtEQ" "" "0.0"
790d10befb2a66192ec1e8a7dcf3243925e315cd7b648b3a63ba855ddd1b52c5
```

---

RPC help before:

```
getactivecrowdsales_MP
getactivedexsells_MP
getallbalancesforaddress_MP address
getallbalancesforid_MP currencyID
getbalance_MP
getcrowdsale_MP propertyID
getgrants_MP propertyID
getproperty_MP propertyID
gettransaction_MP "txid"
listblocktransactions_MP index
listproperties_MP
listtransactions_MP
send_MP
sendrawtx_MP
sendtoowners_MP
```

After:

```
getactivecrowdsales_MP
getactivedexsells_MP
getallbalancesforaddress_MP "address"
getallbalancesforid_MP propertyid
getbalance_MP "address" propertyid
getcrowdsale_MP propertyid
getgrants_MP propertyid
getproperty_MP propertyid
gettransaction_MP "txid"
listblocktransactions_MP index
listproperties_MP
listtransactions_MP ( "address" count skip startblock endblock )
send_MP "fromaddress" "toaddress" propertyid "amount" ( "redeemaddress" "referenceamount" )
sendrawtx_MP "fromaddress" "hexstring" ( "toaddress" "redeemaddress" "referenceamount" )
sendtoowners_MP "fromaddress" propertyid "amount" ( "redeemaddress" )
```