Improved QSS and extinction functions

Improved calculation of QSS mainly for weighted networks, only the nodes/species with self-links/cannibalistic are taken into account for the diagonal of the Jacobian.
Added two functions to calculate the QSS for the network without 1 species/node calc_QSS_extinction_dif, and for a sequence of extinctions calc_QSS_extinctions_seq.

Calc_QSS accept mgraph objects (multiplex networks)

Main update on calc_QSS function to accept multiplex networks and replace foreach with future_lapply

R Package for multiple interaction ecological networks

In development