I like the new common/edge.h. I don't like how inconsistently we use it.
Current situation:
- enum wlr_edges and wlr_direction are designed to be used as bitset,
and are defined compatibly
- enum lab_edge is *also* designed to be used as bitset, but
incompatible with the others (LEFT/RIGHT come before UP/DOWN)
- we use an inconsistent mix of all three *AND* uint32_t (usually with
the WLR_EDGE constants rather than the LAB_EDGE constants), and
convert between them on an ad-hoc basis, sometimes implicitly
Let's clean this up:
- reorder enum lab_edge to be compatible with the two wlr enums
(check this by static_assert)
- use TOP/BOTTOM naming rather than UP/DOWN (matches wlr_edges)
- add constants for the remaining possible combinations of the 4 edges
- use lab_edge for all internal edge/direction fields, consistently
- add lab_edge_is_cardinal() as a sanity check before casting to
enum wlr_direction, and then eliminate all of direction.c/h
Instead of "enum wlr_edges direction", we now have
"enum lab_edge direction" which is not that much better. At least we
are now clear that we're overloading one enum with two meanings.
