Wrappers for Parallel ARPACK with MPI message passing layer have been added. New wrapper classes arpack_worker are defined in a nested namespace ezarpack::mpi and have an API very similar to that of their serial counterparts. Fixed a serious bug in the Blaze storage backend. By default, Blaze adds padding elements to data arrays when storing matrices. This fact was overlooked, which resulted in ARPACK procedures being called with wrong LDV and LDZ arguments. Resolving the issue required adding a new function, storage_traits<Backend>::get_col_spacing(). New accessor arpack_solver::dim() that returns dimension of the eigenproblem. Export a new CMake macro find_arpackng(). It finds a working installation of ARPACK-NG while dealing with version-to-version differences of ARPACK-NG's CMake interface. Drop support for the CMake option EZARPACK_LINK_TO_ARPACK_NG: find_package(ezARPACK) will never try to detect ARPACK-NG.