Edits to SVD section
SVD rank one decomposition
Rename diagonal matrix of SVD
Visualizing SVD subsection
Cholesky decomposition section
Section on determinants outlined
Edits to least-squares section
Edits to generalized eigenspaces
Edits to nilpotent matrices
Edits to Jordan canonical form
Edits to singular value decomposition
Various todo-reminders from 420 course
Minor typo fixed
Edits from SL2X test review
Fix seven cross-references