Squashed 'lectures/' changes from 80e504e..9ea99f2 ...

9ea99f2 Added new lecture document classes & packages • deprecated lecturecombined.cls, lecturenotes.cls, lectureslides.cls • lecturecommon.sty is currently still used by courseoutline.cls,   lectureassignment.cls, lecturefig.cls, and lectureworksheet.cls

git-subtree-dir: lectures
git-subtree-split: 9ea99f2