dat: counts for pointer-table roots

[ribbanya]

Of the 30 roots the code loads into a T**, 28 are tables: null-terminated lists (map_plit in the stage archives, itemdata, the scene light and model lists) or fixed-count tables (the staff roll models, the name tables). The walk followed only their first entry: when the loader gives a root's type, dat_symbols.txt couldn't add a count.

• dat_symbols.txt takes a count:N or count:* attribute, which also applies to roots whose loader gives their type: the walk lays out that many of the root's type, or as many as fit before the next symbol or pointer target (a null-terminated list's null entry included).
• 17 table roots get counts.
• The per-archive types hash includes the count.

Explained relocations 95.0% -> 95.9% (Gm 98.4%, Gr 95.3%, If 99.5%, Mn 99.3%); samples unchanged.