IND2SUBVECT: Multiple subscript vector from linear index.

See IND2SUB for the basic idea. IND2SUBVECT makes a one-line change to IND2SUB so as to return a vector of N indices rather than returning N individual variables. (This makes the function easier to use when the size of the matrix being indexed is not known in advance.) I hope MathWorks will forgive me for adapting their function and/or include this tweak in a future version of IND2SUB.