Remove warning C4239: nonstandard extension used

Remove warning C4239: nonstandard extension used

 * Eliminate warnings such as ...
	`warning C4239: nonstandard extension used: 'argument': conversion
from 'DirItemIterator' to 'DirItemIterator &'`
	`note: A non-const reference may only be bound to an lvalue`
 * These are warnings that only occur with Warning Level == 4.

 * This commit only deals with issues with mixing CString and String
data.
 * Discard the PopString class, a self-admitted hack from
stackoverflow.com, that was simply confusing and not all that "pretty"
anyway.