make new 'referenceonly' docs build the default for offline docs. add preview codename and version number HDF variables for generated docs.
make new 'referenceonly' docs build the default for offline docs.
add preview codename and version number HDF variables for generated docs.

Change-Id: I165526f4e575ec8885bab906e66d17666ea8b4ba

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base