Added the ability to define Views for Attribute Items. This is supported in
Attribute, Instanced, ModelEntityAttribute, and Operator View classes.  Group related views
are not directly effected.

Here is an example:

    <View Type="Instanced" Title="Frequency Information">
      <InstancedAttributes>
        <Att Name="EigenSolver" Type="FrequencyInfo">
          <ItemViews>
            <View Item="NumEigenvalues" Type="Default" Option="SpinBox"/>
            <View Item="FrequencyShift" Option="SpinBox" StepSize="100" Decimals="0"/>
          </ItemViews>
        </Att>
      </InstancedAttributes>
    </View>

The Item attribute is mandatory. If the Type attribute is missing then it is assumed to be
Default.  The rest of the information is then processed by the qtItem class that is being
created. To demonstrate this I have added spinbox options for both IntItem and DoubleItem for their
default qtItem class (qtInputsItem).

This mechanism can be extended to add custom GUI's for items.