signed/unsigned fixes, and some other fixes

src/core/Directory.cpp

@@ -31,7 +31,7 @@ bool
 CDirectory::WriteDirFile(const char *filename)
 {
 	int fd;
-	size_t n;
+	ssize_t n;
 	fd = CFileMgr::OpenFileForWriting(filename);
 	n = CFileMgr::Write(fd, (char*)entries, numEntries*sizeof(DirectoryInfo));
 	CFileMgr::CloseFile(fd);