Support IDispatch

[Rantanen]

We could derive the support for IDispatch interface when implementing COM interfaces. This would allow using Intercom components from dynamic scripting languages.

Unfortunately this requires a lot of other things, such as support for VARIANTs, etc. Not something that will be arriving immediately.

[Rantanen]

This might be on the roadmap. We'll need VARIANTs for SAFEARRAYS, which would be ideal for the collection support in Windows-land.

The initial plan was NOT to support SAFEARRAYS, but now that we came up with multi-interface generation for strings (ie. One trait -> COM interface with BSTRs + COM interface with Intercom strings) we could have the same for collections.

Also... once we get IDispatch we can include Excel as a supported platform!

<dowwie> Rantanen: wow. intercom has great potential
<dowwie> Rantanen: this could allow Rust libraries to run with excel?