Move a table's rows, links and pins into internal/rows, and walk every path through one per-step function, so Fake refuses a level carrying a repeat

CHANGELOG.md

@@ -12,6 +12,9 @@ replacement, and each removed path, column or flag.
   `{/city[Oslo]..country.name}` renders `Norway`, and `.` after it steps down again,
   drawing afresh. `New` refuses a `..` naming anything but the parent table, and a
   selector after a `..`.
+- A path given to `Fake` or the CLI may not read into a level carrying a
+  `repeat`, as a reference may not: `Fake("x.a")` where `x` carries `"repeat": 3` fails,
+  naming the level `x`.
 - Every `{…}` draws afresh, and a name is the one way to keep a pick: `{p.a} {p.b}`,
   `{w} {uppercase(w)}` and `{/person.first} {/person.last}` are two draws each, which
   `{p as q}{q.a} {q.b}` and `{/person as n}{n.first} {n.last}` make one.