Bug 728873 - In Qif importer use the enter on account entry

Focus is already on the account entry so enable the use of the enter
key to proceed to the next page when you are finished changing the
account name for a qif file.

gnucash/gtkbuilder/assistant-qif-import.glade

@@ -381,6 +381,7 @@ Please enter a name for the account. If the file was exported from another accou
                 <property name="primary_icon_activatable">False</property>
                 <property name="secondary_icon_activatable">False</property>
                 <signal name="changed" handler="gnc_ui_qif_import_acct_valid_cb" swapped="no"/>
+                <signal name="activate" handler="gnc_ui_qif_import_acct_enter_cb" swapped="no"/>
               </object>
               <packing>
                 <property name="expand">True</property>

gnucash/import-export/qif-imp/assistant-qif-import.c

@@ -237,6 +237,7 @@ void gnc_ui_qif_import_date_valid_cb (GtkWidget *widget, gpointer user_data);
 
 void gnc_ui_qif_import_account_prepare (GtkAssistant *assistant, gpointer user_data);
 void gnc_ui_qif_import_acct_valid_cb (GtkWidget *widget, gpointer user_data);
+void gnc_ui_qif_import_acct_enter_cb (GtkWidget * widget, gpointer user_data);
 
 void gnc_ui_qif_import_loaded_files_prepare (GtkAssistant *assistant, gpointer user_data);
 void gnc_ui_qif_import_load_another_cb (GtkButton *button, gpointer user_data);
@@ -2134,10 +2135,41 @@ gnc_ui_qif_import_account_prepare (GtkAssistant  *assistant, gpointer user_data)
 }
 
 
+/********************************************************************
+ * gnc_ui_qif_import_acct_enter_cb
+ *
+ * Invoked when the "enter" button is clicked on the acct entry.
+ ********************************************************************/
+void
+gnc_ui_qif_import_acct_enter_cb (GtkWidget * widget,
+                                 gpointer user_data)
+{
+    QIFImportWindow * wind = user_data;
+
+    GtkAssistant *assistant = GTK_ASSISTANT(wind->window);
+    gint num = gtk_assistant_get_current_page (assistant);
+    GtkWidget *page = gtk_assistant_get_nth_page (assistant, num);
+
+    const gchar * acct_name = gtk_entry_get_text (GTK_ENTRY(wind->acct_entry));
+
+    if (!acct_name || acct_name[0] == 0)
+    {
+        /* Disable the assistant "Next" Button */
+        gtk_assistant_set_page_complete (assistant, page, FALSE);
+    }
+    else
+    {
+        /* Enable the assistant "Next" Button and proceed */
+        gtk_assistant_set_page_complete (assistant, page, TRUE);
+        gtk_assistant_set_current_page (assistant, num + 1);
+    }
+}
+
+
 /********************************************************************
  * gnc_ui_qif_import_acct_valid_cb
  *
- * Invoked when the "next" button is clicked on the default acct page.
+ * Change signal for the acct entry to enable "Next" button.
  ********************************************************************/
 void
 gnc_ui_qif_import_acct_valid_cb (GtkWidget * widget,