*The package is now almost entirely designed with S4 classes and methods.
*The time series object are constructed with the 'zoo' package.
*Most of the functions and arguments have been renamed in order to 
ease the understanding by international users.
*Two new functions have been included for the statistical analysis of a PV plant composed of several systems.
*The package dependencies have been optimized.
*Several new small functions for date-time calculations are now available.
*Several bugs have been corrected.