Add console drawing-logic

Add console drawing-logic

A console may be displayed on multiple outputs. We allow different screen
resolutions on these outputs so we need a way to map the console image onto
different outputs.

We simply render the console image into a cairo surface with a user-given
resolution. This should be set to the highest resultion of the used outputs. The
application can now map this image onto the different framebuffers. This will
scale the image if the target framebuffer is smaller than the cairo surface.

We also do not clear the framebuffer. This should be done by the user. This
allows us to draw with alpha values and blend the console on top of the current
framebuffer. We do not have to care for background images and the application
has full control of where the console is shown.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>