#1318 Difference between buffered and unbuffered mode on Direct2D

[Marko Njezic]

When buffered mode is used, auxiliary surfaces are created in a way that makes render target have an alpha channel. This results in inferior greyscale anti-aliasing mode being used when drawing text. Besides this, all underlying code that uses auxiliary surfaces treat them as opaque surfaces and thus they don't even need to be transparent (we can use GDI as an example for comparison). Attached is a patch that fixes this problem with creation of auxiliary surfaces, which will also result in text drawing being the same on Direct2D no matter if using buffered mode or not.

This leaves us now just with the difference in colors between GDI and DirectWrite ClearType implementations due to different gamma values, as mentioned in feature request #3472026.

[Marko Njezic]

[Neil Hodgson]

Committed.