* BIM: minor icon cleanup
* Removed icons used for 'experimental' tools. They are obsolete.
* Updated warning.svg to match .../src/Gui/Icons/Warning.svg
* Renamed Image_CreateImagePlane.svg to BIM_ImagePlane.svg to avoid overwriting the first icon in the Wiki.
* Removed ArchWorkbench.svg and preferences-arch.svg as they are also obsolete.
* To resolve a Wiki name conflict renamed BIM_Project.svg to BIM_ProjectManager.svg, and Arch_Project_IFC.svg to BIM_Project.svg.