3c058fd wallet: Add HasWallets (João Barbosa)
373aee2 wallet: Add AddWallet, RemoveWallet, GetWallet and GetWallets (João Barbosa)
6efd964 refactor: Drop CWalletRef typedef (João Barbosa)
Pull request description:
This is a small step towards dynamic wallet load/unload. The wallets *registry* `vpwallets` is used in several places. With these new functions all `vpwallets` usage are removed and `vpwallets` is now a static variable (no external linkage).
The typedef `CWalletRef` is also removed as it is narrowly used.
Tree-SHA512: 2ea19da2e17b521ad678bfe10f3257e497ccaf7ab9fd0b6647f9d829f1d6131cfa68db8e8492421711c6da399859432b963a568bdd4ca40a77dd95b597839423