When listing files in a file area (directory) configured as "FREE" (no cost to
downlaod), and the "check for file existence" option is enabled, then get the file size as well and display that instead of the credit value. This fixes the problem with files whose size has changed after they were uploaded or added to the filebase. Directories which are not free still displayed with each file's credit value (since that may not have any correlation with the file size). Display file sizes and credit values in a shorter more easy to read format with suffixes for gigabytes (G), megabytes (M), kilobytes (K), and bytes (B). Using an uppercase 'K' now to be more consistent with modern conventions for abbreviating Kilobytes/Kibibyte (1024 bytes).