Wallet: CLN errors for invoices with description hash

[callebtc]

Right now creating a CLN invoice with description hash uses a plugin invoicewithdescriptionhash.

New CLN supports description hash out of the box (see here):

From here:

def invoice(self, amount_msat=None, label=None, description=None, expiry=None, fallbacks=None,
      preimage=None, exposeprivatechannels=None, cltv=None, deschashonly=None, msatoshi=None):

Let's use it.

Need to remove this block from clightning.py

# check description_hash support (could be provided by a plugin)
        self.supports_description_hash = False
        try:
            answer = self.ln.help("invoicewithdescriptionhash")
            if answer["help"][0]["command"].startswith(
                "invoicewithdescriptionhash msatoshi label description_hash"
            ):
                self.supports_description_hash = True
        except:
            pass

Maybe this is also a good opportunity to rename the wallet to cln.py (see if old versions can still import it though).

Todo:

• Update pylightning to pyln-client
• Update wallet documentation where pylightning is referenced
• Get rid of supports_description_hash block
• Rename clightning.py to cln.py?
• Write tests with description hash that should fail with old version

[callebtc]

Fixed in #792.