TORF = HASPQCAP(GEN, HILO) returns a column vector of 1's and 0's. The 1's
correspond to rows of the GEN matrix which correspond to generators which
have defined a capability curve (with sloped upper and/or lower bound on
Q) and require that additional linear constraints be added to the OPF.
The GEN matrix in version 2 of the MATPOWER case format includes columns
for specifying a P-Q capability curve for a generator defined as the
intersection of two half-planes and the box constraints on P and Q. The
two half planes are defined respectively as the area below the line
connecting (Pc1, Qc1max) and (Pc2, Qc2max) and the area above the line
connecting (Pc1, Qc1min) and (Pc2, Qc2min).
If the optional 2nd argument is 'U' this function returns true only for
rows corresponding to generators that require the upper constraint on Q.
If it is 'L', only for those requiring the lower constraint. If the 2nd
argument is not specified or has any other value it returns true for rows
corresponding to gens that require either or both of the constraints.
It is smart enough to return true only if the corresponding linear
constraint is not redundant w.r.t the box constraints.