Add new terms into a column.
coeffs: Coefficients for added constraints; either a list of coefficients or a single coefficient. The two arguments must have the same size.
constrs: Constraints to add to column; either a list of constraints or a single constraint. The two arguments must have the same size.
col.addTerms(1.0, x) col.addTerms([2.0, 3.0], [y, z])