Would like to have owner + ownertype columns rather than owner, group, institution

[Robert Lyon]

So for things like views and artefacts we save the owner id, whether it is user,group,institution id (in this case we'd need to use the institution id rather than name) + owner type, either 'user','group','institution'.

The reasons FOR this are:
1) We can add a uniqueness constraint on the owner/ownertype as they can't allow null values
2) We would start using the institution id instead of passing round the name for better code consistency
3) It would allow easy addition of another ownertype if we wished without having to add more columns

The reasons AGAINST this are:
1) The use of the owner/group/institution is widely used throughout the system so changing anything will take a lot of patches to say the least
2) Create problems for third party plugins