Running.R.from.the.command-line
                        Running R from the Windows Command-line / /
                        Unix Terminal
this.path               Determine Executing Script's Filename
this.path-package       Get Executing Script's Path, from 'RStudio',
                        'RGui', 'Rterm' and 'Rscript' (Command-Line / /
                        Terminal), and When Using 'source'
