Made SwDoc::getDocumentDeviceAccess return a reference.

Also overloaded SwDoc::getDocumentDeviceAccess with its const
version.

Change-Id: I3272be3ee067aa2e0174663ede3c98190ecf2b09
Work on DocumentSettingManager for SwDoc.

Moved mn32DummyCompatabilityOptions1 from SwDoc to DocumentSettingManager
and moved a comment from SwDoc to it.

Change-Id: I4abd5cd9596d23dc3ac12460ee9b38345d0bf0a7