* Added Subpath constructor, iterator and length
* Asserted that subpaths of len < 2 cannot be closed. Added len() and comments
* Added subpath to_svg(), made structs public, made quadratic use either in_handle or out_handle
* add bezier handles
* Added basic interactivity and index traits
* Added SubPath interactivity
* Added svg styling
* Broke subpath impl across multiple files. More sylistic changes per review
* Fixed format error
* Added closed subpath to documentation page
* Modified subpath to_svg to use functional style
* Stylistic changes per review
* Fixed build errors
* More sylistic changes per review
* Moved svg commands to constants
* Moved formatting for svg arguments to ToSVGOptions
* Renamed files in git
* Even more stylistic changes per review
Rob Nadal