FIXED: Do not try to interpret an unset as a term position
ADDED: open/4: create(+AccessList) option to create a new
file with specified modes.
Declare new open/4 option
make decomposition into smaller SAT formulas also work for */1 and +/1 syntax
ADDED: library(prolog_colour): prolog_colourise_query/3 to emit
semantic colours for a query that is to be executed in a given context.
Updated http
MODIFIED: library(prolog_colour): provide file with autoload classified
predicates.