0027721: Add possibility to read STEP file with invalid shape_representation entity.

0027721: Add possibility to read STEP file with invalid shape_representation entity.

Add special parameter, which allow reading of all top level (not shared by any other entities) solids (manifold_solid_brep) and shells (shell_based_surface_model).

The examples how to use a new parameter:

DRAW:
switch on a parameter:
    param read.step.all.shapes On
update model to apply new parameter value:
    newmodel
read as usual:
    stepread test.stp res * // each top level solid or shell will be read as res_i shape.
    or
    ReadStep Doc test.stp

CXX Code:
switch on a parameter:
    Interface_Static::SetIVal("read.step.all.shapes", 1);
read as usual