title: Text alignment control in Shady
body: <p>I'm using Shady to write some text on screen, and I'm wondering what would be the simplest way to control the alignment of the string. From my understanding, the align parameter in a Shady text object controls the paragraph alignment, but I'm interested in controlling the alignment of a single line of text.<br>
  Essentially I'd like to replicate the behavior of the <em>horizontalalignment</em>, <em>verticalalignment</em> and <em>rotation</em> parameters of the matplotlib text function. But to do that I need to estimate the area (in pixels) that will be occupied by the string once rendered. Can I get that out of Shady somehow? In the manual it says that the rendering is done on the CPU and the rendered String is then pushed to the GPU, so it should be doable.</p>