bumping version to 0.2.16.dev for development
set the comment_line string to include the scikit-nano version number
updating docstring formatting
updating docstrings
updating docstrings
adding and updating methods for querying and updating nearest-neighbor property lists
create default_comment_line string and update code to use it when writing structure data
use short_version string in default_comment_line string
updating docstring directives for correct links to Atoms class
updating docstring directives to generate link to Atoms class
renaming atoms to structure_atoms
adding atoms property for backwards compatibility
unhide methods for updating nearest_neighbor lists
new code to allow generating double and triple vacancies in structure data
updating for release of v0.2.16