Add note about parallel plots in the description

Parallel plots are now documented in the "description" section of the
documentation and include a screenshot of the Crawford dataset in
parallel display mode.
Add Exporting and Sharing to the tutorial

The documentation now includes two new sections, one for Exporting and
one for Sharing (thanks for the suggestions @lkursell).

The Exporting tutorial includes a simple example to a command call to
inkscape that converts an SVG formatted file to a PDF.

Fixes #187
Merge pull request #198 from ElDeveloper/doc_updates

Documentation Additions