We have these useful methods, use them.
This begins to allow for constraint-based frame definition.
Try harder to compute frames from limited dimensions.
Declare undeclared variables
The current typesetter should always be SILE.typesetter, as packages/scripts refer to that.
Seems like a recent change to busted dropped automatically requiring assert.
Actually there’s an awful lot we need to do.
Constraint-like frame tests. (This will all be replaced with cassowary soon anyway.)