[AIXM-322] Obstacle visual marking new property

dd a new attribute (“marked”) to VerticalStructure feature to indicate if the structure is marked or not.

Rationale for change

See https://aixmccb.atlassian.net/browse/AIXM-289 

For consistency in the AIXM model, marking and lighting for obstacles should be treated in the same way. For lighting, the VerticalStructure feature includes two attributes that describe its lighting:

• VerticalStructure.lighted – A simple indication that the obstacle is lighted, when no further details are available.
• VerticalStructure.lightingICAOStandard – An indication that the lighting of a vertical structure used as criteria for the ICAO standard as described in Annex 14.

In AIXM v5.1, the VerticalStructure feature includes one attribute that describes its marking, VerticalStructure.markingICAOStandard, which is similar to the lightingICAOStandard attribute. However, there is no attribute to provide a simple indication that the obstacle is marked when no additional details are available. The new attribute VerticalStructure.marked for marking would be analogous to the VerticalStructure.lighted attribute for lighting.

Impact assessment

[FWD_1:1] No data mapping is necessary and no data loss occurs when data is exchanged from a system (A) that uses AIXM 5.1.1 for output towards a system (B) that uses AIXM 5.2 for input.

[BWD_MAP_LOSS] Data mapping is possible, but some data would be lost (or converted into Notes) when data is exchanged from a system (B) that uses AIXM 5.2 for output towards a system (A) that uses AIXM 5.1.1 for input.

Mapping example

(Note: for mapping test data see: https://github.com/aixm/mapping_52_511/tree/master/AIXM-322) 

AIXM 5.2	AIXM 5.1(.1)