add FocusableElement as a subclass of Element. Shapes should derive from it.
put polygon, polyline into their own files. add tests.
update svg.circle and tests.
update svg.path and add tests.
add tests for svg.ellipse and svg.line.
correct string representation of Bezier paths.
improve test coverage for svg.rect and svg.svg.
add several enums dealing with text properties.
svg.text: add multiple-coordinate variants for setters.
rename TextElement => TextOnlyElement to clarify <text> doesn't subclass it.
add TextContentBlockElement to be a common base for <text> and <textArea>.
make svg.text subclass svg.TextAreaBlockElement.
svg.text: add two setters (rotate, text-anchor).
svg.Builder: change implementation of withText(). (Still needs improvement.)
tests: update svg and transform tests to use svg.Builder.withText().
svg.Element: implement setters for some obscure Unicode-related properties.
Add builders for <textArea> and <tspan>. Add tests for those and <text>.
Add builder for <tbreak>.
move Makefile => Makefile.sample and put real Makefile in .gitignore. Document.