avoiding calling both check eigenvalues AND check eigenvalues and
eigenvectors for analytic eigenvector test

if provided a a fourth parameter, all correctness checks will be
skipped. Can be usefull for repeated performance tests.

it seems, that the new compiler interprets order parameter in reshape
command in the opposite way to its predecessor.

previously the orthogonality check has been skipped for generalized EVP

matrix-matrix multiplication restricted to work only with actually
computed nev eigenvectors

Fix some typos in the documentation and examples

See merge request !6