PJ: only build trdfile.lib from fileio.
PJ: delete disisdv1, alternative version of pj_dis_drive.
PJ: remove pj_dtruncate.
PJ: switch to stdio delete file.
PJ: switch to stdio rename file.
PJ: switch to stdio and Watcom's file descriptors.

Using _dos_read/_dos_write as read/write are acting up.