parameterize IDecoratorBox

Signed-off-by: Florian Thienel <florian@thienel.org>
fix subSequence according to contract defined in CharSequence interface

Signed-off-by: Florian Thienel <florian@thienel.org>
set foreground and background color separately

Signed-off-by: Florian Thienel <florian@thienel.org>
convert absolute and relative coordinates

Signed-off-by: Florian Thienel <florian@thienel.org>
add cache for ColorResource to remove amount of short-lived instances

Signed-off-by: Florian Thienel <florian@thienel.org>
add NULL object

Signed-off-by: Florian Thienel <florian@thienel.org>
add interface for boxes that represent parts of the document's content

Signed-off-by: Florian Thienel <florian@thienel.org>
add decoriating box that represents a certain node in the document

Signed-off-by: Florian Thienel <florian@thienel.org>