Additions to Dream public api.

 - lightsOut() -> setLightsOut(boolean)
   (deprecated lightsOut, will remove once all baked-in dreams are updated)
 - Added ability to keep the screen bright (default = false).
 - Lights out is now true by default.
 - Consistent setters(setXxx) + getters(isXxx) for
   interactive, lightsOut, fullscreen, and screenBright dream attributes.
   Can set attributes at any time (even before window is created).
 - Fleshed out javadocs for public api.
 - Reordered things a bit.
 - Added example of manifest dream declaration ready for copypasta.
 - Removed unused action constant, added category constant.

Bug:7172816
Bug:7111868
Change-Id: I721db7a1a5e5ad047a3723b4d5141ef53b0970af