Display Settings: Better font size control

Use a SeekBar instead of a list/spinner to determine the font scaling.
For consistency, an approximate size (small, normal, etc.)
 and the exact percentage are displayed.
Show a preview of the selected font size immediately

Ported from CM 10.2, squashed commits 46678 and 49167.
Credit to Veeti Paaananen for the latter commit.

Change-Id: I754d7fdcaf27c23dfccf9d56291956e70b23f63e
(cherry picked from commit 046894e704e0115d236e9056c3efd51456b4ddd9)

Conflicts:
	res/values/cm_strings.xml
	src/com/android/settings/DisplaySettings.java
settings: add big menu support back
some in our team as well user want it urgently so we do it for
now till new Slim recents is back then we handle it so or so in
another way and do not need the recents button anymore and can
use the big menu button as permanent and get rid off the smal
3dot completly,

Change-Id: I98bc1f0814398af5d7a5d26c28f7edce1c598957
(cherry picked from commit 81fa837df822648c23ffdb925b2103ce959a7644)
Add back hardware key settings.

Change-Id: I925fd9d9c02b86d8e93c8b9e25870433f7c20bde
(cherry picked from commit 2d8443755e6c6bcc0afbca9c51f3ad62aee17475)