Revert "Added missing API, constants..."

This reverts commit 94386a151aeed0b7dc96c6a476cd04aea66077ec.
Revert "Revert "Added missing API, constants...""

This reverts commit b4b63c5332711c2220a20e9bf5599850e9528cee.
Revert (had put VT_ constants already in Variant).
Added missing API