Give targets a tool tip property.

Use that for showing details about connected Symbian devices.
Also update the icon with an (not-)connected overlay icon.
Graphics design pending.

src/plugins/projectexplorer/target.cpp

@@ -214,6 +214,17 @@ void Target::setIcon(QIcon icon)
     emit iconChanged();
 }
 
+QString Target::toolTip() const
+{
+    return m_toolTip;
+}
+
+void Target::setToolTip(const QString &text)
+{
+    m_toolTip = text;
+    emit toolTipChanged();
+}
+
 QVariantMap Target::toMap() const
 {
     const QList<BuildConfiguration *> bcs = buildConfigurations();