this function masks the builtin "clear" and carefully checks to make sure that "all" (or the default zero-argument case, which MathWorks foolishly made equivalent to "all") is not in the argument list. It accepts any mixture of string and cell arrays of string arguments.
Further, this function checks whether it was called from the console. If not , i.e. was called from within a function, it reverts to the builtin "clear" function so that function environments can be cleared as would normally happen.
With thanks to Cris Luengo and Andrew Janke over at StackOverflow.