documentation I have calls them, and update for new definitions in
sys/exec_ecoff.h. Also, fix ECOFF_SEGMENT_ALIGNMENT macro so that it
actually returns the right alignment.
Support for AXPpci CPUs,
Support for AlphaStation 600 CPUs,
new boot block structure, which requires an 'installboot'
program and works a lot like the NetBSD/sparc boot blocks.