Add wall posts entry to structuralWallElementType

[sdeinert]

In order to realistically model the structure of fuselage walls crossing other structural components (e.g. bulkheads, other walls, ...) the definition of wall posts would be required.
The logic of a wall post is to add a structural line element to the intersection lines between a wall an other structural components and assign it some physical properties similar to the wing rib posts or upper/lower caps of spars and ribs. This would allow modelling the added stiffness of the extra material needed to bolt or bond the wall to other components intersecting with it.
The proposed extension to the structuralWallElementType would be an optional posts element of type capType:

<xsd:element name="posts" type="capType" maxOccurs="1" minOccurs="0">
  <xsd:annotation>
    <xsd:documentation>Reinforcements at intersection lines with other fuselage structure components (e.g. pressure bulkheads, other walls, etc.)</xsd:documentation>
  </xsd:annotation>
</xsd:element>

The following screenshot shows the geometry of the wall posts in red.
Note: Only the upright wall has posts defined in this case so that the "floor" wall does not show these lines on its intersections.