Camera2: Maintain focus mode when using ttf

Add an option to maintain the focus mode when using
touch-to-focus

There's at least one family of camera HALs that gets "confused" when
the focus mode forcefully changes to auto after setting focus /
exposure area options.

Sticking with the current focus mode still results in effective use
of the focus region, so don't force a switch to auto. The default
behavior remains the original, this needs to be explicitly enabled
on affected devices

Change-Id: Icf70eb749cdfadd7c2739e41a9841681f2f3d561
Camera2: added enhanced scene mode menu

Based on CM

Change-Id: Id10da1b5aec9f61dfe3ef0ebdc4e5f0a180af66e
Camera2: added slow shutter support

For N1

Change-Id: Ice6dd2219054cb02a3191ae3484c44824fc6bee5
Merge remote-tracking branch 'omni/android-4.4' into omni-4.4