More Planner improvements

• Fixed a bug that prevented to scroll the rack on iPad when you dragged a Module
• 1U Modules cannot be dropped in 3U rows anymore
• you can no longer drop a module halfway between two rows—it will snap to one of them. In rare cases, this may trigger the Cat of Dread.
• minor CSS fixes. If you try to add a module to a locked rack, you will now see a more visible colored warning instead of the approval thumbs-up which was unintended kind of passive aggressive.

EDITED Tuesday March 31, 12:35