Multiple or partial INTERSECT function

INTERSECTN allows > 2 inputs and finds partial intersects! Much more flexible than intersect alone!

% INTERSECTN functions similarly to INTERSECT, but has some added
% flexibility. For example, if you input three arrays and want to find
% items that are in at least two of them, INTERSECT is incapable of doing
% this, but INTERSECTN will do it.
%
% OUT = INTERSECTN(IN1,IN2,...,MATCHES)
%
% Inputs: IN1,IN2,... are cell arrays of strings or numerical vectors.
% MATCHES is a scalar, the number of matches that are required.
%
% For example, if you have three sets of fruit names, and you want to
% return any fruits that show up in at least two of these sets, use:
% OUT = INTERSECTN(IN1,IN2,IN3,2)
%
% Example:
% fruit{1} = {'apple','banana','cherry','orange'};
% fruit{2} = {'apple','cherry','lemon','tangerine'};
% fruit{3} = {'apple','lemon','lime','peach'};
% fruit{4} = {'apple','lemon','orange','coconut'};
%
% out = intersectn(fruit{:},4)
% returns: 'apple'
%
% out = intersectn(fruit{:},3)
% returns: {'apple','lemon'}
%
% out = intersectn(fruit{:},2)
% returns: {'apple','cherry','lemon','orange'}