Move blocks with keyboard controls

[tracygardner]

• Workspace doesn't scroll to block when added from toolbox
• Top level blocks don't switch order with constrained move
• Undo of move takes too many steps for for complex blocks
• When a block is added to the top-level workspace it is not disabled

[tracygardner]

When the workspace was selected, adding a block from the toolbox with keyboard controls didn't scroll the workspace to the newly added block.

fcf1d9d removes a workaround that was preventing the workspace from scrolling.

[tracygardner]

Non top-level blocks added in move mode directly to the workspace are now disabled (previously they were left enabled until a manual move event. 6cb175f