DOC: Get clp(b) into the manual
Add clp(b) to the Windows installer
Updated http
Preparing version 7.1.20
ADDED: CLP(B): Tentative version of sat(card(Is,Fs)),
       constraining the number of true expressions in the list Fs to
       be a member of the list of integers Is.

         Example:

             ?- sat(card([2],[X,X*Y,Z])), labeling([X,Y,Z]).
             %@ X = Z, Z = 1, Y = 0 ;
             %@ X = Y, Y = 1, Z = 0.
DOC: CLP(B) now supports card(Is,Exprs) in Boolean expressions.
FIXED: backtrace() on Windows can fail if a symbol handler installed on a previous call has not been deallocated
Updated http
ENHANCED: CLP(B): Make attribute names SWISH-friendly.
FIXED: library(sandbox) declaration for nb_setval/2.
ENHANCED: Make library(clpb) tracktable by the sandboxing code.
Updated pengines
ADDED: library(sandbox): del_attrs/1 is safe.
SECURITY: library(sandbox): setting attributes can also cause calling
of Attr:attribute_goals//1.  Markus Triska.
FIXED: Sandbox declarations for library(clpb).
FIXED: library(apply_macros): expanding maplist(SomeMetaPredicate, ...)
was just `mostly correct'. This, together with the fact that sandboxing
cannot deal with the required transparent directive and there is
apparently some inner meta-calling, which makes getting rid of the outer
meta-calling less important made me decide not to expand maplist/N if
the argument is a meta-predicate.  Found by Markus Triska, nesting
maplist calls.
Updated pengines
use b_get/setval to reuse nodes and variable IDs
ENHANCED: library(sandbox): Allow b_setval/2 and b_getval/2 when the first argument is instantiated.