WIP sicp course p1 work.

- first half of the problem set is answered.
- Added unit testing to the problem set.
finished the solution to P1 of sicp with tests.

- still need to edit the tests into one suite.
- in the symbolic derivatives question the test checks both
  a symbolic solution and a numeric one.
Changed the file to include tests in a sub-module.

- racket docs, suggest using a sub-module of a module for testing.
- add test.rkt for the use with a general solution.
- you can now run test.rkt from DrRacket.