v0.12.1-rc.1

Added

• RasterMath use available memory to speed up process and manage now several cores (n_jobs)
• train_test_split in cross_validation module

Changed

• Enhance mask management for RasterMath
• Move FlushCache to optimize RasterMath
• RasterMath get_random_block returns only block which are not totally unmasked
• charts.PlotConfusionMatrix has a default argument (zero_is_min=True)