Bitcoin-Qt: fix known addressbook bugs

- add qSort() for cachedAddressTable, as qLowerBound() and qUpperBound()
  require the list to be in ascending order (see
  http://harmattan-dev.nokia.com/docs/library/html/qt4/qtalgorithms.html#qLowerBound)
- add a new check in AddressTableModel::setData() to just return, when no
  changes were made to a label or an address (prevents entry duplication
  issue)
- remove "rec->label = value.toString();" from
  AddressTableModel::setData() as the label gets updated by
  AddressTablePriv::updateEntry() anyway (seems @sipa added this line via
  1025440184 (L6R225))
- add another new check in AddressTableModel::setData() to just return, if
  a duplicate address was found (prevents address overwrite)
- add a new check to EditAddressDialog::setModel() to prevent setting an
  invalid model
- re-work the switch-case statement in AddressTableModel::accept() to
  always break (as return get's called anyway) and order the list to match
  the enum definition
- make accept() in editaddressdialog.h a public slot, which it should be
- misc small coding style changes

src/qt/editaddressdialog.cpp

@@ -25,7 +25,7 @@ EditAddressDialog::EditAddressDialog(Mode mode, QWidget *parent) :
         break;
     case EditReceivingAddress:
         setWindowTitle(tr("Edit receiving address"));
-        ui->addressEdit->setDisabled(true);
+        ui->addressEdit->setEnabled(false);
         break;
     case EditSendingAddress:
         setWindowTitle(tr("Edit sending address"));
@@ -44,6 +44,9 @@ EditAddressDialog::~EditAddressDialog()
 void EditAddressDialog::setModel(AddressTableModel *model)
 {
     this->model = model;
+    if(!model)
+        return;
+
     mapper->setModel(model);
     mapper->addMapping(ui->labelEdit, AddressTableModel::Label);
     mapper->addMapping(ui->addressEdit, AddressTableModel::Address);
@@ -58,6 +61,7 @@ bool EditAddressDialog::saveCurrentRow()
 {
     if(!model)
         return false;
+
     switch(mode)
     {
     case NewReceivingAddress:
@@ -82,35 +86,39 @@ void EditAddressDialog::accept()
 {
     if(!model)
         return;
+
     if(!saveCurrentRow())
     {
         switch(model->getEditStatus())
         {
-        case AddressTableModel::DUPLICATE_ADDRESS:
-            QMessageBox::warning(this, windowTitle(),
-                tr("The entered address \"%1\" is already in the address book.").arg(ui->addressEdit->text()),
-                QMessageBox::Ok, QMessageBox::Ok);
+        case AddressTableModel::OK:
+            // Failed with unknown reason. Just reject.
+            break;
+        case AddressTableModel::NO_CHANGES:
+            // No changes were made during edit operation. Just reject.
             break;
         case AddressTableModel::INVALID_ADDRESS:
             QMessageBox::warning(this, windowTitle(),
                 tr("The entered address \"%1\" is not a valid Bitcoin address.").arg(ui->addressEdit->text()),
                 QMessageBox::Ok, QMessageBox::Ok);
-            return;
+            break;
+        case AddressTableModel::DUPLICATE_ADDRESS:
+            QMessageBox::warning(this, windowTitle(),
+                tr("The entered address \"%1\" is already in the address book.").arg(ui->addressEdit->text()),
+                QMessageBox::Ok, QMessageBox::Ok);
+            break;
         case AddressTableModel::WALLET_UNLOCK_FAILURE:
             QMessageBox::critical(this, windowTitle(),
                 tr("Could not unlock wallet."),
                 QMessageBox::Ok, QMessageBox::Ok);
-            return;
+            break;
         case AddressTableModel::KEY_GENERATION_FAILURE:
             QMessageBox::critical(this, windowTitle(),
                 tr("New key generation failed."),
                 QMessageBox::Ok, QMessageBox::Ok);
-            return;
-        case AddressTableModel::OK:
-            // Failed with unknown reason. Just reject.
             break;
-        }
 
+        }
         return;
     }
     QDialog::accept();