check vintage version and create

Usage

check_and_create(dir, vintage, DATE, clean, verbose)

dir: character: output directory
vintage: character: name of output folder. It could be "latest", "new", or any other name. if it is "latest" (default), the most recent version available in the vintage directory of the form "%Y%m%d" will be used. If it is "new", a new folder with a name of the form "%Y%m%d" will be created. All the names will be coerced to lower cases
DATE: character: date of the form "%Y%m%d"
clean: logical: if TRUE it cleans all empty directories that have been created by mistake. Default is FALSE.
verbose: logical: display messages. Default is getOption("pipload.verbose")