Replaces command {update,full,full/rec} by build/{update,full,full/rec}
Implements 'make build/product/<product_name>'
Implements 'make show/products/all'
Lets 'make build/update' build only public products' targets
Implements 'make show/targets/all'
Adds the MK_DEPENDENCIES variable containing all files' global dependencies
Implements 'make clobber'
Implements 'make trash' and lets 'make clean' prune the build directory content