Re-use text.dat entry NoErrorLogExists for reporting DirectoryDoesNotExist and

changed FileNotThere text.dat entry to FileDoesNotExist which displays the file
path.
Now check if the directory exists before checking the available disk space
before allowing file uploads and report the correct error (using
DirectoryDoesNotExist) if the directory is missing (a common mistake).
Overhaul viewfilecontents() - wow, I can't wait to re-write all of this moldy
filebase code!