* Removing m_xLngMgr.is() check from SfxThesSubMenuHelper::GetThesImplName was
  unsound with SfxThesSubMenuHelper ctor swallowing Exception; best fix appears
  to be to remove the swallowing.

* Prefer forward declarations over #includes.

Change-Id: Ie4e7dcd6cdb14046516d119605bbf78e81359768