Mouse release signal, confirmation for saving, others

Tools can now act on mouse releases.
The Run tool can click on components
   New button component reacts to this

Some component labels changed

New and load now ask for confirmation if the circuit was changed
   Still no undo/redo yet

Component/Wire rendering is now based on the grid size
   A tile has a size of 1x1, display is scaled based on that

Status bar shows current tool and mouse position

Removed Move tool - all components can pan the view by middle clicking