Tabstops.reset subtracted one from the column count before iterating
default stops. Although init and resize accept zero columns, resetting
that state with a nonzero interval underflowed and panicked.
Return after clearing when the grid has fewer than two columns. Empty
and single-column tabstop sets now preserve the normal no-stop result.
As of Zig 0.14.0, `@splat` can be used for array types, which eliminates
a lot of redundant syntax and makes things generally cleaner.
I've explicitly avoided applying this change in the renderer files for
now since it would just create rebasing conflicts in my renderer rework
branch which I'll be PR-ing pretty soon.
Fixes#359
See #359 for a test script. The unit tests were also wrong. I used the
test script in #359 to verify the exact column that tabstops should be
set at.
