XSB Src (SVN)-old

Forgot to add psc_immutable code.

Changes t0o support immutable declaration.

minor err message improvement

in error_write(ln)/1, added the ++Error[XSB: prefix
in string.P, added read_atom_to_term_print_on_error. This is similar to
read_atom_to_term, but also prints out syntax errors and not just fails.

updated the config files

the change is in build/windows*/def_config.in
Turns out MS VC++ 2015 finally defined snprintf, so now we have to check is the version is >= 1900 then also define HAVE_SNPRINTF in VC++

The other changes are due to a rerun of configure

Fixed compiler register allocation (actually register freeing) bug pointed
out by Paulo Moura. This is very focussed fix and may not fix the other
examples Paulo had. (I assume this will be checked...)

Depth -> size in flags.

Changed flags: depth -> size and started to add tripwires.

Updates for flag changes and revisions for tripwires