Upcoming major version changes

[pnorman]

We've got a couple of upcoming or proposed changes which will break backwards compatibility

#668 changes slim internals and forces a reload of existing databases. This impacts a fair number of users, but is a change to internals so won't require any code changes from others

#659 and possibly connected #605 (comment) would involve a behavior change. For the multi-backend it's not going to impact anything existing, but is a change for lua and c transforms.

Some other suggested but undecided changes were defaulting -G (#660)