[ outcell, iIn, iOut ] = uniqueCells( incell [, 'rows', 'equalnan'] )

Usage is similar to unique().
The 'rows' switch returns unique rows in a matrix of cells. Otherwise, ND cell arrays are supported.
The 'equalnan' switch treats NaNs as equal.

As sorting is not possible for mixed-type cells the output corresponds to
the 'stable' switch in unique(). The occurrence-switch of unique() is NOT
implemented.

The following is true (w/o the 'rows' switch'):
isequal(incell(iIn), outcell)
isequal(outcell(iOut), incell)

Using the 'rows' switch:
isequal(incell(iIn,:), outcell)
isequal(outcell(iOut,:), incell)

The algorithm performs exhaustive pairwise comparisons using isequal
making it exact and type-independent (in contrast to implementations
using num2str); however this may come at the expense of performance.