An more idiomatic access to the Canvas API.

Aims to be particularly minimalistic and close to the original thing (cf. README).

Functions producing side effects are organized in a fluid interface. In other words, they return the given context or
standalone path and can conveniently be be chained using `->`.

Shape drawing functions, such as [[line]] or [[arc]], can be applied both to contexts as well as standalone
paths produced by [[path]].

Functions prefixed with `path-` only apply to standalone paths and mimick other functions applying only to contexts.
For instance, [[path-stroke]] is the sibling of [[stroke]].