Modify sort

updated the sort function so also the original table is passed to the sort function, so the values can be examined (as I needed to put table values last in the list).

NOTE: the sort function takes 3 parameters, key-list, original table, and then the option provided.
That last parameter I do not get. It is either a function or a boolean, so it will never make a difference. Unless I'm  missing something, that parameter could be dropped.

NOTE2: current sorting puts capitalized keys first, dunno whether that is on purpose or not. The example in the updated readme.md does case-insensitive sorting.