Allow querying the lowest possible brightness

Used by the auto-brightness adjustment to adjust the sliders.

允许调用尽可能低的亮度

被自动亮度控制用来调整亮度滑块.
Don't adjust volume when vol-downing to vibrate or silent

Pressing vol-down to vibrate or silent would (previously) still adjust the
stream volume, setting the last audible volume to 0, which is not allowed
for voice-capable devices.  Thus, the last audible volume would reset to
default on reboot if on vibrate/silent or the lowest volume setting.

By not adjusting volume when vol-downing to vibrate or silent on
voice-capable devices, the last audible volume is always preserved across
reboot.

当长按音量下至震动或静音时不要调整音量

长按音量下至震动或静音时, (曾经)依然会调整音量至最小值,
而这在可语音通话的设备上是不被允许的. 因此, 在震动/静音
或最小音量的情况下, 在重启后, 会重置至默认音量.

而此项改变可以让长按音量下至震动或静音后, 能在重启时
维持当前音量.
[1/2] LED customization

* Add LED customization.
* Add global and per-app settings.
* Set default LED color as white.
* Remove stock on/off checkbox and add an dedicated category.
* Comment out dead code from display settings.

[1/2] 个性化LED

* 添加LED个性化.
* 添加全局和各个应用的设置.
* 设置默认LED颜色为白色.
* 删除原生开/关勾选框, 并添加一个独立分类.
* 将显示设置中的无用代码加为评论.

[2/2] in platform_packages_apps_Settings

Thanks to CyanogenMod for the original implementation.
感谢CyanogenMod原创实现此功能.