The names of reflection API functions were previously confusing.
They included weird patterns that only made sense inside the Cur
implementation.
As they are Racket functions, they ought to somehow indicate that these
functions are for Cur, which they did not.
Created split packages: cur, cur-lib, cur-test, cur-doc, similar to
other Racket packages, e.g., redex.
* Moved tests out of core and into cur-test
* Moved docs into cur-doc
* Moved cur implementation and libraries into cur-lib
* Added cur meta-pacakge that installs all of the above
