Edited Issue: IActiveScriptSiteWindow implementation [73]

Hello,

I've added an implementation for IActiveScriptSiteWindow to the WindowsScriptEngine.ScriptSite class which allows the user to provide a window handle for parenting dialogs. The code can be found at:

https://lr-senergy.kilnhg.com/Code/ODM-OpenSource/Group/ClearScript

or in the attached patch.

Currently EnableModeless is not implemented - this could be made to fire an event in the WindowsScriptEngine class, perhaps.

If it's possible to merge this (or a version of it) into the official codebase, that would be great.

Thanks, Owen