Brush tool

[mbasaglia]

A tool that can be used like brushes in raster graphics software.

• [ ] New tool
• [ ] Dragging the mouse merges new insertion commands, release and won't any more. (Implement either as a mergeWith command or as a macro)
• [ ] Customizable brush
• [ ] ^ number of nodes
• [ ] ^ distance between them
• [ ] A new tile is placed when the mouse moves a greater distance than the size of the brush
• [ ] New nodes connect to previous nodes
• [ ] If a node already exists, it's used that instead of a new node.