Добавил экран FAQ со всеми описаниями

lib/purchase.dart

@@ -14,10 +14,6 @@ class PurchaseScreen extends StatefulWidget {
 
 class PurchaseScreenState<T> extends BaseState<T> {
 
-  PurchaseScreenState() {
-    
-  }
-
   String integerPart = '', fractionalPart = '';
 
   @override String getTitle() {
@@ -30,8 +26,8 @@ class PurchaseScreenState<T> extends BaseState<T> {
 
   @overide getMenuButtons(BuildContext context) {
     return <Widget>[
-      new IconButton(icon: new Icon(Icons.help_outline), onPressed: () {}), 
-      new IconButton(icon: new Image.asset(logout_png, height: iconHeight, width: iconHeight), onPressed: () => logout(context))
+      new getFaqButton(), 
+      new getLogoutButton()
     ];
   }
 
@@ -71,7 +67,7 @@ class PurchaseScreenState<T> extends BaseState<T> {
         integerPart = tmpString;
         controller.text = tmpString;
       }
-      textFieldValue = controller.text;
+      textFieldValue = tmpString;
     });
   }