Better install wizard

Break out the workflow logic of the install wizard
into a base class.  This means reimplementing with
full support in a new GUI is now easy; you just provide
ways to request passwords, show messages etc.  The API
is fully documented in the base class.

There are a couple of minor outstanding issues, including that
the old messages shown when recovering a wallet are missing.
I will come back to that.  Ledger wallet might be broken.

Other improvements:

The install wizard code is now easy to follow and understand.
Hardware wallets can now be restored without any need for their
accompanying libraries.
Various bits of trustedcoin were broken and have been fixed.
Many plugin hooks can be removed.  I have only started on this.

plugins/trezor/qt_generic.py

@@ -1,11 +1,10 @@
 from functools import partial
-from unicodedata import normalize
 import threading
 
 from PyQt4.Qt import QGridLayout, QInputDialog, QPushButton
 from PyQt4.Qt import QVBoxLayout, QLabel, SIGNAL
 from trezor import TrezorPlugin
-from electrum_gui.qt.main_window import ElectrumWindow, StatusBarButton
+from electrum_gui.qt.main_window import StatusBarButton
 from electrum_gui.qt.password_dialog import PasswordDialog
 from electrum_gui.qt.util import *
 
@@ -66,11 +65,12 @@ class QtHandler(PrintError):
 
     def passphrase_dialog(self, msg):
         self.dialog_stop()
-        d = PasswordDialog(self.windows[-1], None, None, msg, False)
-        confirmed, p, phrase = d.run()
+        d = PasswordDialog(self.windows[-1], None, msg,
+                           PasswordDialog.PW_PASSHPRASE)
+        confirmed, p, passphrase = d.run()
         if confirmed:
-            phrase = normalize('NFKD', unicode(phrase or ''))
-        self.passphrase = phrase
+            passphrase = TrezorPlugin.normalize_passphrase(passphrase)
+        self.passphrase = passphrase
         self.done.set()
 
     def message_dialog(self, msg, cancel_callback):
@@ -104,52 +104,30 @@ class QtPlugin(TrezorPlugin):
     #   pin_matrix_widget_class
 
     def create_handler(self, window):
-        return QtHandler(window, self.pin_matrix_widget_class, self.device)
+        return QtHandler(window, self.pin_matrix_widget_class(), self.device)
 
     @hook
     def load_wallet(self, wallet, window):
         if type(wallet) != self.wallet_class:
             return
-        self.print_error("load_wallet")
-        wallet.plugin = self
-        self.button = StatusBarButton(QIcon(self.icon_file), self.device,
-                                      partial(self.settings_dialog, window))
-        if type(window) is ElectrumWindow:
+        try:
+            client = self.get_client(wallet)
+            client.handler = self.create_handler(window)
+            client.check_proper_device(wallet)
+            self.button = StatusBarButton(QIcon(self.icon_file), self.device,
+                                          partial(self.settings_dialog, window))
             window.statusBar().addPermanentWidget(self.button)
-        if self.handler is None:
-            self.handler = self.create_handler(window)
-        msg = wallet.sanity_check()
-        if msg:
-            window.show_error(msg)
+        except Exception as e:
+            window.show_error(str(e))
 
-    @hook
-    def installwizard_load_wallet(self, wallet, window):
-        self.load_wallet(wallet, window)
+    def on_create_wallet(self, wallet, wizard):
+        client = self.get_client(wallet)
+        client.handler = self.create_handler(wizard)
+        wallet.create_main_account(None)
 
-    @hook
-    def installwizard_restore(self, wizard, storage):
-        if storage.get('wallet_type') != self.wallet_class.wallet_type:
-            return
-        seed = wizard.enter_seed_dialog(_("Enter your %s seed") % self.device,
-                                        None, func=lambda x: True)
-        if not seed:
-            return
-        # Restored wallets are not hardware wallets
-        wallet_class = self.wallet_class.restore_wallet_class
-        storage.put('wallet_type', wallet_class.wallet_type)
-        wallet = wallet_class(storage)
-
-        handler = self.create_handler(wizard)
-        msg = "\n".join([_("Please enter your %s passphrase.") % self.device,
-                         _("Press OK if you do not use one.")])
-        passphrase = handler.get_passphrase(msg)
-        if passphrase is None:
-            return
-        password = wizard.password_dialog()
-        wallet.add_seed(seed, password)
-        wallet.add_cosigner_seed(seed, 'x/', password, passphrase)
-        wallet.create_main_account(password)
-        return wallet
+    @staticmethod
+    def is_valid_seed(seed):
+        return True
 
     @hook
     def receive_menu(self, menu, addrs, wallet):
@@ -162,6 +140,8 @@ class QtPlugin(TrezorPlugin):
 
     def settings_dialog(self, window):
 
+        handler = self.get_client(window.wallet).handler
+
         def rename():
             title = _("Set Device Label")
             msg = _("Enter new label:")
@@ -172,7 +152,7 @@ class QtPlugin(TrezorPlugin):
             try:
                 client.change_label(new_label)
             finally:
-                self.handler.stop()
+                handler.stop()
             device_label.setText(new_label)
 
         def update_pin_info():
@@ -186,7 +166,7 @@ class QtPlugin(TrezorPlugin):
             try:
                 client.set_pin(remove=remove)
             finally:
-                self.handler.stop()
+                handler.stop()
             update_pin_info()
 
         client = self.get_client()
@@ -234,8 +214,8 @@ class QtPlugin(TrezorPlugin):
         vbox.addLayout(Buttons(CloseButton(dialog)))
 
         dialog.setLayout(vbox)
-        self.handler.push_window(dialog)
+        handler.push_window(dialog)
         try:
             dialog.exec_()
         finally:
-            self.handler.pop_window()
+            handler.pop_window()