Note the presence of the linear algebra library in *FEATURES*.
MIT copyright on all files.
Return the type of a specific array element.
Kernel routines for matrix inversion.
New fundamental operation, invert.

Invert a matrix.
Improve the common-class-of function using the class precedence list.
Remove exports for triangular matrices that are no longer defined.
Use INITIALIZE-INSTANCE to remove initialize-vector and simplify make-vector.
Simplify MAKE-MATRIX using INITIALIZE-INSTANCE and INITIALIZE-MATRIX-CONTENTS.