  In this paper, we present a new version of the $i$QIST software package,
which is capable of solving various quantum impurity models by using the
hybridization expansion (or strong coupling expansion) continuous-time quantum
Monte Carlo algorithm. In the revised version, the software architecture is
completely redesigned. New basis (intermediate representation or singular value
decomposition representation) for the single-particle and two-particle Green's
functions is introduced. A lot of useful physical observables are added, such
as the charge susceptibility, fidelity susceptibility, Binder cumulant, and
autocorrelation time. Especially, we optimize measurement for the two-particle
Green's functions. Both the particle-hole and particle-particle channels are
supported. In addition, the block structure of the two-particle Green's
functions is exploited to accelerate the calculation. Finally, we fix some
known bugs and limitations. The computational efficiency of the code is greatly
enhanced.
