Added some usefull stuff

[N1CK145]

Whats new?

• You can add chats by method
• You can add Message by method
• Addressbook - Stored all Cotacts
• Contacts - Relation betweeen addess and name
• Message - Message (transaction)

[leto]

@N1CK145 plz change firstname to fullname and lastname to nickname

See https://www.w3.org/International/questions/qa-personal-names for some reasons. Also:

• It's valid to have an empty nickname
• fullname must be unique (in our local addressbook), independent of nickname
• nickname must be unique (in our local addressbook), independent of fullname
• It's not valid to create a contact with no fullname
• Full name can contain any characters at all, no limitations, with max limit of 128 bytes
• Nick name can contain any characters at all, no limitations, with max limit of 128 bytes

[leto]

@N1CK145 this is not necessary, but additionally: The data model of a message/memo probably should have a txid which is the transaction it is included, as well as a height which is the block height the transaction is included in. height should default to -1 which means "not included in any block yet". This will be used by the GUI to show if a memo has made it out of the mempool and into an official block, which is the first step to becoming "notarized" and then permanent.