BoxingDeclarationVisitor #999: visit shortcut refinements as if they were regular methods
ClassTransformer #999: Set the initialise/specifier on shortcut methods/attrs

Rather than try to deal with it ourselves, because that was incorrectly treating
lazy attributes as if they were eager.
ClassTransformer: comments
ClassTransformer: fix for #1018 and #1020: missing @Override and extra attributes defined in $impl classes

We only need attributes in $impl if they are not formal
Temporary partial fix for #1019: captured attributes/methods in classes from outer interfaces need $this prefix
Fixed tests .src for #1018: remove useless getters in $impl
Updated tests for #1020: @Override missing on every lazy attribute
Test for #999: shortcut method refinement
Updated tests for ** to ^ renaming
The old ^ operators for sets are gone now
BoxingDeclarationVisitor #999: Make sure we treat specifier statements as refining their decl

When they are not refinement shortcuts, specifier statements for methods have their own
model for their parameters that we need to take care of.
Fixed .src for #1019: Attributes captured in classes from their outer interface not prefixed with $this
Updated test for #620 now that the latest typechecker changed something