directory was being created always (it should only be created if there are
files to be placed in there).

but fixes filenames for all upper/lower DOS filename compatibility.

No longer calls closedir with NULL pointer if opendir fails.

Each function that requires a temp string variable, now has its own "tmp" local variable.

Pkzip/unzip required *.* to add/extract all files in a directory. <sigh>

un_qwk no longer deletes packet file (responsibility of caller).
Updated bracket style.