Proposal to add the attribute "rotation" to <TerminalGraphicalRepresentation>

[TorstenBlochwitz]

There is currently no way to define the rotation of the icon of a Terminal. According to section 2.4.9.1.2 CoordinateSystem we allow flipping only:

Flipping of the FMU icon or a terminal can be realized by setting its attributes x2 < x1 or y2 < y1 without changing the coordinate system.

This makes it hard to have Terminals at the upper or lower side of an FMU icon.

A workaround would be to provide rotated bitmaps, but this makes it hard for an importer with a GUI to define a direction into a connection line should go first. And it disables the re-usage of icon-bitmaps.

For that reason we propose the introduction of the new attribute "rotation". We propose a similar semantics as it is used in Modelica language: The rotation attribute specifies the rotation of the graphical item counter-clockwise in degrees around the center of the rectangle spanned by x1, y1 and x2, y2.