-threshold for quasi extinction in stages.csv and LifeStage.cpp
-statistics files (full and mean)
-disturbances.csv: renamed iLon, iLat to xCoord, yCoord
-Environment.cpp: storing delta timesteps
-LifeStage.cpp: storing (mean) statistics --> meanDensity, lastPeak, meanPeak, lifetime, nPeaks, nQuasiExt
-Population.cpp:  storing (mean) statistics --> meanDensity, lifetime, nExt
-main.cpp: updated --help, creating stats output, output per sqm,