Reorganize wrapper functions into functionally-related files/classes

[sneurlax]

• WalletManager
• Wallet
• Transactions
• Address Book
• Listeners & Event Handling
• Coins
• Subaddresses
• Multisig
• Device Management
• Utility & Validation
• Transaction Utilities
• Debugging & Testing
• Miscellaneous Utilities

[sneurlax]

We don't even have a lot of these categories of functions wrapped yet, mostly having focused on WalletManager and Wallet functions. So this issue will be here for awhile until these bindings mature.

Maybe we should look into binding generation?