Added "elements_Leslie" function

Test on 10 scenarios !

+ some minor eolpop-package cleaning

We don't include newborns (age class 1) into the population count.

Also modified "pop_project" functions accordingly

Made expert-elicitation distri plots look nicer

Created function run_simul_shiny

Added choice of model_demo inside the run_simul function using the set of decisions rules based on :
* lambda (growth vs decline) for DD
* lambda and N0 (small vs large pop) for StochDemo

Updated other functions accrodingly