Improvements to accessibiity

Where  tool  tips are  defined  in  rich  text, equivalent  pain  test
accessible descriptions have been added  so that screen readers do not
announce HTML tags.

Refactored date time  delegates to use a simpler default  editor via a
default  item editor  factory for  QDateTime values,  the editor  is a
standard QDateTimeEdit with a format that includes seconds and renders
assuming the time is UTC.

Modified the Cabrillo log and Fox log database table models to provide
QDateTime items  for the edit role  of date time fields,  and formated
date time strings including seconds and assumed as UTC for the display
role.

models/FoxLog.cpp

@@ -21,6 +21,23 @@ class FoxLog::impl final
 public:
   impl (Configuration const * configuration);
 
+  QVariant data (QModelIndex const& index, int role) const
+  {
+    auto value = QSqlTableModel::data (index, role);
+    if (index.column () == fieldIndex ("when")
+        && (Qt::DisplayRole == role || Qt::EditRole == role))
+      {
+        auto t = QDateTime::fromMSecsSinceEpoch (value.toULongLong () * 1000ull, Qt::UTC);
+        if (Qt::DisplayRole == role)
+          {
+            QLocale locale;
+            return locale.toString (t, locale.dateFormat (QLocale::ShortFormat) + " hh:mm:ss");
+          }
+        value = t;
+      }
+    return value;
+  }
+
   Configuration const * configuration_;
   QSqlQuery mutable dupe_query_;
   QSqlQuery mutable export_query_;