A Mesh tool click within the hit tolerance outside a gradient mesh hit the
mesh, but object.mesh.addLine looked for the point inside the outline only
and failed with "point is outside the mesh". The same click on a path's edge
made a 1x1 mesh without the line.
- GradientMesh::locate_within takes a tolerance: a point outside the mesh
within it of the outline gives the nearest point of the edge.
- object.mesh.addLine and object.mesh.create take an optional `tolerance`
(0 by default), and the Mesh tool sends its hit tolerance.
dotCooCoo