Add DB upgrade script to change generic type names to undecorated ones

Author: tamasvajk

csharp/ql/src/semmle/code/csharp/Type.qll

@@ -56,7 +56,7 @@ private predicate isObjectClass(Class c) { c instanceof ObjectType }
  */
 class ValueOrRefType extends DotNet::ValueOrRefType, Type, Attributable, @value_or_ref_type {
   /**
-   * DEPRECATED: use `getUndecoratedName()` instead
+   * DEPRECATED: use `getUndecoratedName()` instead.
    *
    * Gets the name of this type without `<...>` brackets, in case it is a generic type.
    */

csharp/ql/src/semmlecode.csharp.dbscheme

@@ -1,3 +1,13 @@
+/* This is a dummy line to alter the dbscheme, so we can make a database upgrade
+ * without actually changing any of the dbscheme predicates. It contains a date
+ * to allow for such updates in the future as well.
+ *
+ * 2021-07-14
+ *
+ * DO NOT remove this comment carelessly, since it can revert the dbscheme back to a
+ * previously seen state (matching a previously seen SHA), which would make the upgrade
+ * mechanism not work properly.
+ */
 
 /**
  * An invocation of the compiler. Note that more than one file may be