'hydroPSO': immproved checking of some arguments; 'random.update' only used when 'best.update'=async, and more and better examples. 'text\_functions': corrected name of the 'rastringin' function, and corrected definition of the 'shafferF6' function

Fixed error that appeared when the 'plot_out' function was called from an R script running directly on the OS console (not within the R editor), with the following error message: 'Error in plot2(x = sim, y = obs, plot.type = single, main = paste('Daily',  : could not find function 'hasArg'

new 'random.update' parameter for the 'control' variable, in order to allow random update of personal/global best

hydroPSO: default value of the inertia weight 'IW' was changed from (linearly decreasing) IW.w= c(1.2, 0.4) to 'IW.w=1/(2*log(2))'

hydroPSO: fixed small bug related to improper PSO evolution when 'best.update==async'. source code was tidy up. Added '...'  parameter.