loadfiles() will perform liberal filename matching when len > 12 chars
As discovered while making the Synchronet v3.18b feature video (https://www.youtube.com/watch?v=_IWzIV0_sZ4), when only a shortened version of a long filename is displayed (e.g. due to 80 column terminal width limitations), trying to download that filename by specifying the filename at the Download File(s) Filespec [All Files]: prompt can be problematic. For example (as seen in the video), the file "SyncTERM-1.1-setup.exe" is displayed as "SyncTERM.exe" (on an 80-column terminal), yet trying to download "SyncTERM.exe" (or "syncterm.exe") using the 'D'ownload command would fail to find a file with that name (understandably, but frustratingly so). This change will transform the requested filename-to-load if it is at least 12 characters in length and contains no wildcards (* or ?), to include a filename extending wildcard: "filename.txt" will become "filename*.txt" and "longfilename" will become "longfilename*". For requested filespecs of NULL (all files) or specs containing wildcards or specs (filenames) less than 12 characters in length, no filespec transform takes place: so trying to list/download "a" doesn't match "apple.txt".