Remove TopoDS_Shape from TopoDS_Shape

Dear Thiago Macedo.

- The class TopoDS_Shape is root class for all types (vertex, edge, etc).
So, try to get the type of your shape aS.ShapeType() before removing smth from it.
- The types of shapes are declared in TopAbs.cdl as the follwing:

enumeration ShapeEnum is
---Purpose: Identifies various topological shapes. This
-- enumeration allows you to use dynamic typing of shapes.
-- The values are listed in order of complexity, from the
-- most complex to the most simple i.e.
-- COMPOUND > COMPSOLID > SOLID > .... > VERTEX > SHAPE.
-- Any shape can contain simpler shapes in its definition.
-- Abstract topological data structure describes a basic
-- entity, the shape (present in this enumeration as the
-- SHAPE value), which can be divided into the following
-- component topologies:
-- - COMPOUND: A group of any of the shapes below.
-- - COMPSOLID: A set of solids connected by their
-- faces. This expands the notions of WIRE and SHELL to solids.
-- - SOLID: A part of 3D space bounded by shells.
-- - SHELL: A set of faces connected by some of the
-- edges of their wire boundaries. A shell can be open or closed.
-- - FACE: Part of a plane (in 2D geometry) or a surface
-- (in 3D geometry) bounded by a closed wire. Its
-- geometry is constrained (trimmed) by contours.
-- - WIRE: A sequence of edges connected by their
-- vertices. It can be open or closed depending on
-- whether the edges are linked or not.
-- - EDGE: A single dimensional shape corresponding
-- to a curve, and bound by a vertex at each extremity.
-- - VERTEX: A zero-dimensional shape corresponding to a point in geometry.

COMPOUND,
COMPSOLID,
SOLID,
SHELL,
FACE,
WIRE,
EDGE,
VERTEX,
SHAPE
end ShapeEnum;