Spreadsheet part marking fails when all cells are entered

[chrismgraham]

There seems to be an issue with marking when all cells in a spreadsheet are filled in. See e.g. the example at https://numbas.mathcentre.ac.uk/question/150943/fill-in-a-table-of-values/preview/. Part marks and feedback is given if some of the cells are completed correctly, but filling all cells marks incorrect.

[christianp]

Whoops - I introduced a typo when I changed the mark_ranges note. Now fixed.