Scriptdictionary
A scriptdictionary is a dictionary which has string keys and script values.
It is defined with nested <item> keys for each key/value pair.
For example:
<useon type="scriptdictionary">
<item key="object1">
msg ("you use object1")
</item>
<item key="object2">
msg ("you use object2")
</item>
</useon>
