RPC: add blocknotify, walletnotify

[zgreat]

Don’t see any documentation on the following features from bitcoin could you let me know if I can use them with this project?

blocknotify= Execute command when the best block changes (%s in cmd is replaced by block hash)
walletnotify= Execute command when a wallet transaction changes (%s in cmd is replaced by TxID)

[gdassori]

No but, definitely an interesting feature so, not yet.

[gdassori]

blocknotify first draft w.i.p. 5224da5

[zgreat]

Awesome mate thanks for taking the time to work on it cheers!