Added table to sem parameter estimates for indirect effect of environment via forest structure.
In fit_sem_models: making tables and figures of indirect and direct effects.
In fit_varpart_models: fitting univariate glm-nb models and testing for AIC supported quadratic terms.
Add models to univariate plots.
added function for variance partitioning
added lots of new figures for analyzing SEM model output. removed old figures to OLD CODE section
now using variation partitioning on hetero/optimality and regional/local. not on variable type. not using hier.part anymore. new figures showing variation partitioning results. evaluates univariate model parametrization (quadratic effects, glm distribution)
univariate plots include best model. new four-panel bw figure including richness ~ abundance