Cleanup platform builders #64
Description
Platform builders needs an overall cleanup to seamless the user experience. Some bugs remains e.g. in cleanup from previous builders. This includes:
- anchors are not properly removed when changing from one builder to the other (DONE)
- anchors that are not in the current plane are still displayed
- anchors size is not normalized on the path, in particular when putting anchors on a platform
- hole builder displays anchors outside of a platform, or outside of the currently modified platform
- walls doesn't allow to create closed wall structures