Simplify invoices and requests.

- We need only two types: PR_TYPE_ONCHAIN and PR_TYPE_LN
 - BIP70 is no longer a type, but an optional field in the dict
 - Invoices in the wallet are indexed by a hash of their serialized list of outputs.
 - Requests are still indexed by address, because we never generate Paytomany requests.
 - Add 'clear_invoices' command to CLI
 - Add 'save invoice' button to Qt

electrum/gui/qt/paytoedit.py

@@ -61,7 +61,6 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         self.errors = []
         self.is_pr = False
         self.is_alias = False
-        self.is_lightning = False
         self.update_size()
         self.payto_address = None
         self.previous_payto = ''
@@ -143,6 +142,7 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
             except:
                 pass
             if self.payto_address:
+                self.win.set_onchain(True)
                 self.win.lock_amount(False)
                 return
 
@@ -153,12 +153,13 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
             except:
                 self.errors.append((i, line.strip()))
                 continue
-
             outputs.append(output)
             if output.value == '!':
                 is_max = True
             else:
                 total += output.value
+        if outputs:
+            self.win.set_onchain(True)
 
         self.win.max_button.setChecked(is_max)
         self.outputs = outputs