Compute NFD for non-feasible communities

Added a new file numerical_NFD_permanence which can compute niche and fitness differences for communities where not all species survive. It searches for the surviving species by solving the differential equation and then automatically identifies the surviving species and computes niche and fitness differences for both, surviving and non-surviving species.
This code is available in both R and Python.

Include intra-specific facilitation into niche and fitness differences

The repository now contains the files to include intra-specific facilitation into niche and fitness differences

V1.0.1

Add meta-data

Building modern coexistence theory from the ground up: the role of community assembly

V1.0.0-alpha

Add R code for permanence