Change API of QStaticText::setMaximumSize() to setLineWidth()

setMaximumSize() is limiting. There's no need to require that people calculate the height of the text prior to using QStaticText. Use setLineWidth() to be symmetrical with QTextLayout. This will only affect line breaks. People can set a clip on the painter themselves if this is also required.

This will also require some rethinking on part of the different interpretation of the position of the text when the line width is set and not. It doesn't make sense to have different interpretations. We should stop mirroring the behavior of drawText() exactly and just start interpreting the position as the top left of the text always. This is easier to explain and more predictable.