Always look at content even when reversing

[stuartlangridge]

If someone edits the content of a cell (or custom key) while the table's already sorted by that column, then if we sort by it again sorttable will just reverse or re-reverse the column and not notice that the content has changed. Devices now are probably fast enough to schwartzian the content always and not bother with the "just reverse without looking" optimisation, although we still need to record which direction the table is sorted in anyway so we know to reverse it.

[rlaphoenix]

Really need this. Especially since im adding over 100 new rows a minute.