- Added interpolation option for interpolation of images, default true.

see #1608

unified border calculation. Needs to be centralized to avoid duplication.

- Fixed #1528, #1278, avoided ID's being cast to string for methods that return ID's as well as storePositions casting to string.

Node labels don't currently make use of the 'align' property, so this reuses
the existing property.

The label code has a number of alignment options that make sense to edges only,
so the Edge/Node now passes a boolean to the Label ctor to explain which the label
is being rendered for

Theoretically, there are multiple node shape types that this could apply to.

Will only apply to Network nodes with a shape: 'box' property, as most
other shapes this will not make sense for. This enables the box shape
to be used, for instance, for diagraming CFG data from source code.

Changed shapeProperties.borderDashes type description from "Object or Boolean" to Array or Boolean".
Merged circularImageWithDashedBorder example into shapesWithDashedBorders example.
Added enableBorderDashes and disableBorderDashes function calls to Database.js, Ellipse.js and Box.js, to enable/disable dashed borders.

Replaced dashes property in options.js with a shapeProperties object containing a borderDashes property.
Replaced dashes property in defaultOptions in NodesHandler.js with shapeProperties object having its borderDashes property set to false.
Created implementations of enableBorderDashes and disableBorderDashes functions in NodeBase.js
Updated CircleImageBase to use enableBorderDashes and disableBorderDashes for enabling/disabling dashed borders.
Added to ShapeBase enableBorderDashes and disableBorderDashes calls to allow all shapes that have borders to have the dashed borders feature.
Updated example demonstrating how to apply the dashed border to a circularImage node
Created example demonstrating how to apply the dashed border to a all shapes that support dashed borders.
Updated documentation explaining the usage of the shapeProperties.