Enable sub-pixel rendering

There appears to be broad agreement that this behavior change is an improvement for large fonts and variable width fonts, but there is fervent argument that it's a regression for small monospace fonts. Discussion on #ubuntu-devel yielded a compromise proposal to use fontconfig to select the previous LCD filter behavior for fonts with small pixelsizes. All parties seem to be happy with this proposal, so I will also be happy to accept such an implementation for the beta.

Updated source packages (and debdiffs) of the packages which include the patches that Matthew wanted are now available here:

    http://people.ubuntu.com/~scott/lcdfilter/

The fontconfig-config package ships with a default configuration that uses the legacy lcd filter for Monospace fonts that will appear at 12px or less.

Matthew has withdrawn his objections, however has noted a possible problem with the use of Slight hinting; we reached a decision about that already though:

<mjg59> Ok, let me see how this turns out in a minute
[...]
<mjg59> Keybuk: Ok, playing with hinting seems to suggest that stuff Just Works
<Keybuk> mjg59: your monospace appears with legacy lcd filtering?
<mjg59> Keybuk: Yup
<Keybuk> ok, seems that we're both happy now? :)
<mjg59> Keybuk: Hm. No, I've got some very ugly rendering here with slight hinting
<mjg59> Hang on, let me try to figure this out
<mjg59> Ok. I'd say at the moment that this change plus full hinting seems to work fine
<mjg59> Slight hinting is generating severe colour blurring
<Keybuk> mjg59: yeah, I've alternated between Full and Slight for a while ...
<Keybuk> I think the upload should not include the gnome-control-center change, and instead the mail should ask people to compare both and see which they like
<mjg59> Keybuk: Yeah, I'd go with that for now

Uploaded