[REF] Rename 'pos' to something more meaningful

[christophKaiser]

The parameter name pos is used in many functions of the geometry converter. It describes the transformation of the geometry coordinates to place an object in its place. A change request brought up that the parameter name does not really fit.

In the discussion and in a dev-meeting, the suggestion objectPlacement was decided to be a more meaningful name.

File which is being refactored
Many files in the namespace IfcGeometryConverter.

Functions
Basically, all functions in the IfcGeometryConverter could be affected and should be checked (at least with the auto-search/-replacement tool).