Turbo Prolog 2.0. Changes from 1.x.

 Turbo Prolog 2.0 change list

- external database support with protected memory access

- BGI interface support

- improved text editor

- ability to save trace to file

- integers overflow check

- stack check

- error level

- ability to call prolog predicates from Turbo C

- conditional compilation support  (ifdef, ifndef, elsedef, enddef)

- standart trap predicate

- build with Turbo C 1.5