* Gram-Schmidt using vector type
* QR decomposition
* Operator 1-norm and maximum norm; stub for 2-norm and angle between
subspaces (`matrix-basis-angle')
* `matrix-absolute-error' and `matrix-relative-error'; also predicates
based on them, such as `matrix-identity?'
* Lots of shuffling code about
* Types that can have contracts, and an exhaustive test to make sure
every value exported by `math/matrix' has a contract when used in
untyped code
* Some more tests (still needs some)
* Split "matrix-constructors.rkt" into three parts:
* "matrix-constructors.rkt"
* "matrix-conversion.rkt"
* "matrix-syntax.rkt"
* Made `matrix-map' automatically inline (it's dirt simple)
* Renamed a few things, changed some type signatures
* Fixed error in `matrix-dot' caught by testing (it was broadcasting)
* Rewrote matrix comprehensions in terms of array comprehensions
* Removed `in-column' and `in-row' (can use `in-array', `matrix-col' and
`matrix-row')
* Tons of new rackunit tests: only "matrix-2d.rkt" and
"matrix-operations.rkt" are left (though the latter is large)
