use dialog functions properly
move alloc_memory early to prevent core dump at stage 3
Change 25x80 to 24x80
Fix setenv diagnostic
Fix Fatal to call end_dialog()
Re-organised files, moved bootcode routines into their own files.
Check return types of everything and pass error messages to
windows so we get good diagnostics.
Made start on stage 2 installation. Implemented a status file that
keeeps track of where we are in the installation process and allows
installation from media sequences.