Add support fo *.ttinclude

[iwhp]

At the moment only *.tt files are support. Please also add *.ttinclude support for color highlighting. Thank you!

[olegsych]

That's a good idea, @iwhp :+1: Thanks for submitting it.

I think this only requires exporting an additional FileExtensionToContentTypeDefinition to associate .t4 extension with the TextTemplate content type in the TemplateContentType.cs.

[multinerd]

any progress on this?

[olegsych]

PRs are welcome 😄.