fix handling of subqueries in query design

- don't remove parentheses around subqueries
   (without the parentheses, it is not valid SQL)
   * when saving a Field (name value) typed by the user interactively
   * when parsing SQL and constructing the initial Query Design view

 - automatically add the necessary parentheses
   when a SELECT statement is entered as column name

Also:

In code saving a Field (name value) typed by the user interactively,
factorise some common code

Assorted minor fixes (typos in comments, etc)

Change-Id: I3843258323c903cba23238b0730ec4eb5875f792

dbaccess/source/ui/querydesign/QueryDesignView.cxx

@@ -2202,7 +2202,8 @@ namespace
                     pColumnRef = pColumnRef->getChild(0);
                     OTableFieldDescRef aInfo = new OTableFieldDesc();
 
-                    if (    pColumnRef->count() == 3 &&
+                    if (    pColumnRef->getKnownRuleID() != OSQLParseNode::subquery &&
+                            pColumnRef->count() == 3 &&
                             SQL_ISPUNCTUATION(pColumnRef->getChild(0),"(") &&
                             SQL_ISPUNCTUATION(pColumnRef->getChild(2),")")
                         )