The current make_layer function has a `None` default for the shape color and the line color. With that value the current preference is used. This, and how the function is called, results in some confusing behaviors:
* Newly created layers will only use 2 values from the preferences when they might use 5. The latter makes more sense for the end-user IMO.
* Layers created during DXF import (for example) will have a different shape color depending on the current preferences.
* The make_layer function may reapply colors that have already been set by the view provider.
To solve this all view property related function parameter have been changed to a not None value. If a None value is supplied the view property as set by the view provider is not changed. The Layer Manager has been updated accordingly.
I realize that calling a function with 6 None values is not very convenient, but think it is the solution that is least likely to break other exiting code.
Additionally:
* Removed the makeLayer function. Layers were introduced in V0.19 when the naming scheme was changed to "make_*". Maybe it was created by mistake, or before the actual renaming operation started, but it is safe to remove it now.
* Removed overly verbose messages.
* gui_layers.py had a missing import (result of a previous V0.22 PR): `from draftutils import utils`.
Move `make_layer` to `draftmake`; `Layer` and `LayerContainer`
to `draftobjects`; `ViewProviderLayer` and `ViewProviderLayerContainer`
to `draftviewproviders`.
The make function and the classes are imported in `Draft.py`
to support the usage of the older `VisGroup`.
