Version 0.9.0

StructuralProxyElement: Object that defines a solid. Contains boundary representation geometry information.

BoundaryRepresentationGeometry: Object that holds the vertex and face definitions of a solid. Please note that no definition of "edges" are involved. The face definition refers to the indexes of the vertices.

Face: Object used to define a face in a BoundaryRepresentationGeometry. This was needed because we needed to support openings as well, hence the list of loops inside the object. Rule of thumb is: when there's only 1 loop, it's a closed face. Any additional loops represent openings in the face.

Added validator for StructuralProxyElement. Must have Material and Geometry. For Geometry, we check that there are at least 3 vertices defined. Regarding the faces, we check if each loop on a face has at least 3 vertex indexes and that those indexes are valid.

StructuralLoadCase: Removed Specification property as it was not used.

FlexibleEnum: Added implicit conversion operators and equality operators. These allow you to cast an enum value or a string value to FlexibleEnum. The equality operators allow you to compare a FlexibleEnum instance with an enum value or a string.