Don't pass redundant label names to table_width and list_start

[Rangi42]

RGBDS 0.9.0 introduces the string symbols . for the current global label scope and .. for the current qualified local label scope. These allow us to get the "current label" in the table_width and list_start macros without having to redundantly pass it.

(The reason we want the current label at all, instead of always generating a new local label with \@ to mark the start of a table or list, is so that when the size is wrong, the error message will mention the name of the thing that's wrong instead of some obscure autogenerated label.)

If this looks good, I'll do the same in red+yellow+gold.

[Rangi42]

These commands were very helpful:

git grep -l table_width | xargs sed -i -E 's/^(.)table_width ([^,]+), [A-Za-z0-9_.]+$/\1table_width \2/g'
git grep -l list_start | xargs sed -i -E 's/^(.)list_start [A-Za-z0-9_.]+$/\1list_start/g'

[Rangi42]

Okay, @dannye and @mid-kid also approved :)