Update do-matrix to work with new subscripting code
Add more arithemtic cases, including ./
Export ./
Wait to evaluate range values until after macroexpansion

This allows passing local variables to ranges
Add LU-decomposition and determinants, hooray!

(let ((r (map:random-matrix 100 100)))
  (time (map:determinant r)))

  Evaluation took:
  0.531 seconds of real time
  0.530000 seconds of total run time (0.527000 user, 0.003000 system)
  [ Run times consist of 0.033 seconds GC time, and 0.497 seconds non-GC time. ]
  99.81% CPU
  2,123,710,686 processor cycles
  364,958,480 bytes consed

So, there's some work to be done.
Fix one or two mistakes in the new plotting code