0028188: Improving layer color storage mechanism for DXF Import/Export

0028188: Improving layer color storage mechanism for DXF Import/Export

Attribute ColorByLayer was added for shapes that should be colored by the color of their layer or, if it's absent, by the parent component's layer color.

Fixing inconsistency of iterating through the map of Styles

Improving ColorByLayer mechanism

Fix for Map/IndexedMad differences.

Renaming according to convention of naming collection typedefs