Examine RPC support

[shane-kerr]

We might not have full RPC functionality for everything that the wallet supports.

If this is true, we should add it.

Even if we do have support, we should make sure that we output a meaningful error message if someone tries to call something that we do not support.

[shane-kerr]

A small change which will output the name of functions that do not exist is here:

https://github.com/shane-kerr/Mintcoin-Desktop-Wallet/tree/improve-rpc

[shane-kerr]

An audit by Enlil reveals:

MORE (12)
checkwallet
getcheckpoint
gethashespersec
getnewpubkey
getwork
getworkex
makekeypair
repairwallet
resendtx
reservebalance
sendalert
validatepubkey

MISSED (39)
abandontransaction
addnode
clearbanned
createmultisig
decodescript
disconnectnode
dumpwallet
estimatefee
estimatepriority
estimatesmartfee
estimatesmartpriority
fundrawtransaction
generate
getaddednodeinfo
getbestblockhash
getblockchaininfo
getblockheader
getchaintips
getmempoolinfo
getnettotals
getnetworkhashps
getnetworkinfo
getrawchangeaddress
gettxout
gettxoutproof
gettxoutsetinfo
getunconfirmedbalance
getwalletinfo
importaddress
importpubkey
importwallet
listbanned
listlockunspent
lockunspent
ping
prioritisetransaction
setban
verifychain
verifytxoutproof