Dash-bio

Changed
* Made Speck component compatible with refactored Speck library.
* Optimized Speck component further to increase performance.

Added
* Added default props to Molecule3dViewer component.
* Added zoom/pan and export SVG capabilities to Circos.

Added
* Added Molecule2dViewer component.

Changed
* Refactored Speck component and implemented general bug fixes.

Fixed
* Fixed issue with Speck not responding to preset changes.

Removed
* Removed all parsing tools in `dash_bio.utils` to a separate package,
`dash_bio_utils`.

Added
* Added to xyz_reader the ability to handle whitespace at the
beginning and end of a line (in data file).
* Added a working link to the JS distribution, so serving scripts
locally is no longer necessary.

Fixed
* Fixed homepage link in package metadata.

Fixed
* Fixed issue with Clustergram rows and columns reordering incorrectly
on the heatmap when precomputed traces are used to generate the
figure.
* Fixed issue with Speck not rendering unless it is attached to a
callback.
* Prevented Speck from trying to calculate a system with no atom.
* Let Clustergram render even when row and column labels are not
specified, by adding default values.
* Allowed multiple SequenceViewer components to render on the same
application.

Changed
* Changed Clustergram to only return a figure by default, so that
values no longer need to be unpacked.
* Changed Molecule3dViewer's `selectionType` prop to accept all-
lowercase values.

Added
* Added to Clustergram the ability to generate a "curve dictionary" to
translate curve number (available in hoverData/clickData) to the row
or column cluster it represents on the graph.