d3d: Report errors on download/blit/upload.
d3d: Dynamically size the drawPixelsTex_ like gl.
d3d: Fix download of small sections, oops.
d3d: Dirty the shader when drawing textures.
d3d: Use StretchRect() when possible.
d3d: If possible, use StretchRect() to display.

May be faster, has less half-pixel offset issues.  Still seeing blurriness
problems, but they're better.