Readline-to-Racket: Use racket everywhere.

Readline-to-Racket: Rename file to mzrl.rkt to rktrl.rkt
Browser-to-Racket
Update the browser collection to use Racket lang instead of mzscheme.
Move algol-60 collection from mzscheme to racket lang.
-remove mzlib and mzscheme imports
-Small cleanups.
-Ensure tests pass.
-Small indentation fixes