change "lookup" command to "check" command and display more info

A "check" function would be useful, instead of "id", to display more info :

check <pubkey> gives :

• identity is it is a member account
• identity status (pool/BC)
• <pubkey>:<checksum>
• "virgin" wallet (with or without in/out txs)

check <pubkey>:<checksum> gives :

• <pubkey> if right checksum ; WRONG PUBKEY if not
• identity is it is a member account
• identity status (pool/BC)
• "virgin" wallet (with or without in/out txs)

check <identity> gives:

• <pubkey> if existing identity // NON-EXISTING IDENTITY if not
• identity status (pool/BC)
• <pubkey>:<checksum>
• "virgin" wallet (with or without in/out txs)

For now, no Duniter client gives the pubkey + checksum, although it is a useful information.

Maybe the checksum should be displayed separately. This should be discussed.