Editing the description of 'Value' primitive subtype shows empty form

[HatefulMoron]

Editing the description of 'Value' of, for example, 'BatteryChemistryType' does not work and instead shows an empty form.

This is due to this line -- Value itself does not have an entry to refer to in the object, it should either look for ValueString or omit this check.

This line should also probably be changed to look for Value<Type>. nodeParentOBPrimitiveValueType may be useful.