Numeric histref aliases for slot fields

[haase]

When display/describing a table, create numeric alias references for the slots in the table, e.g.
#[;; #17
foo 3 ;; #17,1
bar 9 ;; #17,2
]
with #17,0 mapping back to #17. Possibly display the slot based reference also, e.g.
#[;; #17
foo 3 ;; #17,1 = #17#foo
bar 9 ;; #17,2 = #17#bar
]

Additional idea: have sequence/choice offsets be 1-based and have the original be the zero reference.

And one more possibility, restore symbolic history refs of the form #.symbol.