Best management of height and altitude for sources and receivers.

[pierromond]

Users should be able to specify the height and/or altitude of a source or receiver from the HEIGHT or ALTITUDE fields and not just from the (x,y,z) field.

By default, the z-height for the POINTZ indicates the height in NoiseModelling which can lead to misunderstandings (classicaly it is more altitude), moreover, many users have difficulty dealing with 3D geometries.