Squashed 'lectures/' changes from 38c9d6c..03790f4 ...

03790f4 Migrated to iftex package

git-subtree-dir: lectures
git-subtree-split: 03790f4

Squashed 'lectures/' changes from dc30efe..3e812cc ...

3e812cc Reduced spacing after answer environment

git-subtree-dir: lectures
git-subtree-split: 3e812cc

Squashed 'lectures/' content from commit 2b1085b ...

git-subtree-dir: lectures
git-subtree-split: 2b1085b