Added additional test cases to help identify text rendering bugs.
Don't mess with the layout.
Fixed style inheritance issue.
Reimplemented SVGTextElement to not use CATextLayer, to get the flexibility in text rendering needed. Added basic support for tspan elements.

Fixed issues:
SVGTextElement creates blurred text (https://github.com/morgendagen/SVGKit/issues/1)
SVGTextElement does not handle current text position correctly (https://github.com/morgendagen/SVGKit/issues/2)