Squashed 'External/Lagrangian/' changes from 7eb40a3..622703f

622703f Import headers from the framework.

git-subtree-dir: External/Lagrangian
git-subtree-split: 622703f2bdb75207288cfc3eb2efed64e1b613b8
Merge commit '20ce6fb3295ceef440f9af55affd3b22ecf73062' into develop
Change the dependencies such that L3 can be used without being required to be built.