Sort a table in ascending order of specified columns.
x xasc y xasc[x;y]
Where x is a symbol vector of column names defined in table y, which is passed by
y sorted in ascending order by x.
The sort is by the first column specified, then by the second column within the first, and so on.
The sorted attribute is set on the first column given (if possible). The sort is stable, i.e. it preserves order amongst equals.