-Replace codes.h with iberror.h (or remove)
-Move gds__vax_integer and gds__event_block* to alt.cpp and isc_ to gds.cpp
-Use ISC_QUAD internally
-Use isc_vax_integer internally
placed some variables in context
fixed some function signatures
closed a few possible buffer overruns
sorry to the platform maintainers, I can't verify what I did for non-Win32 builds