Introduce a tool that can be used to create and edit a paths

[sprocketc]

We need to implement a tool that can be used to create paths under src/renderer/tool/impl/element/path.cljs. We also need to improve element.hierarchy/render-edit under src/renderer/element/impl/shape/path.cljs to allow editing paths (also see the d attribute spec).

We already have svgpath installed, that can be used to parse the segments from the d string attribute of the path, like (-> el :attrs :d svgpath .-segments), to get a list of segments like the following

[
    [
        "M",
        180.733125,
        76.48709375
    ],
    [
        "H",
        380.7687812499999
    ],
    [
        "V",
        173.03478124999998
    ],
    [
        "H",
        180.733125
    ],
    [
        "V",
        76.48709375
    ],
    [
        "z"
    ]
]

The complex part is that the feature requires bezier curve editing. We should use the circle-handle for the curve editing and the square-handle for the points, that live under renderer.tool.views.