Fix issue where Share Avatar Collections imported from FTN were saved as files

in data/fido with the node number encoded twice (once in hex and once in
decimal):
006702c1.705.VERT.misc.bin

This is a harmless bug, but an unintentional one. It would also result in
unexpected filenames in text/avatars:
705.VERT.misc.bin

So... this commit should remove the "705." from these filenames.

exec/avatars.js

@@ -195,7 +195,9 @@ function import_shared_file(hdr, body)
 
 	// If the filename (in the subject) already contains the sender's QWK-ID, skip-it
 	var filename = file_getname(hdr.subject);
-	var prefix = file_getname(hdr.from_net_addr) + '.';
+	var prefix = '';
+	if(!fidoaddr.is_valid(hdr.from_net_addr))
+		prefix = file_getname(hdr.from_net_addr) + '.';
 	var suffix = '.bin';
 	if(filename.length > prefix.length + suffix.length
 		&& filename.substr(0, prefix.length).toLowerCase() == prefix.toLowerCase())