Fix discretization with interval matrices for inputs not containing 0

[schillic]

The corrected algorithm can be found in [1], Algorithm 4, p. 49 (and some definition on p. 47).

[1] M. Althoff: Reachability analysis and its application to the safety assessment of automonous cars

[mforets]

Draft (from gitter):

if homogeneous
    R = CH(X0, e^Ar*X0) + F*X0
elseif origin in U
    R = CH(X0, e^Ar*X0) + F*X0 + Ω0_inhomog
else
    P(r) = ...
    Chull = CH(X0, e^Ar*X0 + P(r)) + -1 * P(r) + F*X0 + F~*u~ + Ω0_inhomog
end