Added the ability to specify a clip tolerance.

The clip tolerance can be set now. Default is FLT_EPSILON. Setting to too
large a value will cause numerical problems.

Change-Id: Icc332801ed4b9f00b6b6c58cb78b0a36186f4729
Fixed bug causing plane to disappear on boundary.

When the plane was moved to one of the sides of the bounding region, and
was parallel to the bounding region, it sometimes disappeared. To fix this
the origin of the plane is clamped to slightly within the bounding region.

Change-Id: Ie4c22df9faf9d6dc739dd542f07df136f0784e9d
Create vtkPolyData instead of vtkUnstructuredGrid when passing points.

This is a feature / performance request.

Change-Id: I3f8745a4591f19a8ce0960ae82af328816b4e6fa
Added "sticky" axes mode to vtkCubeAxesActor

This change adds a mode to vtkCubeAxesActor that keeps the axes in the
viewport by changing the boundaries of the axes to keep them all
within the viewport. It works by computing the largest sphere that
will fit in the view frustum at the depth of the original bounding
box's center, then computes a cube that fits within that sphere.  The
final bounding box is the intersection of the original bounding box
and the cube that fits within the sphere. If this intersection is
empty, the bounds are invalidated so that no axes are displayed.

The sticky axes mode also has a centering option that controls whether
the truncated bounding box stays centered in the viewport or follows
the center of the original bounding box along the longer of the two
viewport dimensions. Whether this option is enabled or not, the axes
are restricted to being within the viewport.

Change-Id: I6dc3cd4127d2e4da8f2580fd2242ffa51270629a
Merge topic '0013436-vtkBandedPolyDataContourFilter-ClipTolerance' into master

b04dd36c Added the ability to specify a clip tolerance.
Merge topic '0014369-vtkExtractSelectedIds-Output-vtkPolyData' into master

c1d37686 Create vtkPolyData instead of vtkUnstructuredGrid when passing points.
Merge topic '0014066-vtkImplicitPlaneWidget2-disappears' into master

91045594 Fixed bug causing plane to disappear on boundary.
Added canvas based image zooming and panning capabilities.

Change-Id: I374931fd5f448da694d36edb2ee3e6aa4c6e2731
Merge topic 'vtkweb-add-zoom-pan-catalyst-viewer' into master

ab674b27 Added canvas based image zooming and panning capabilities.
Merge topic 'sticky-axes' into master

5040362b Added "sticky" axes mode to vtkCubeAxesActor
Fixed a null reference by surrounding the call with a check.

Change-Id: Ib9f0e85c1fe26e7a1a1efd02000be4a9240e6ff5
Merge topic 'vtkweb-add-zoom-pan-catalyst-viewer' into master

119cc10d Fixed a null reference by surrounding the call with a check.