In the HtDP languages, initial subexpressions that have evaluated to
#t / #f remain in the residual term, whereas in the DMdA languages,
they do not.
svn: r16018
removed htdp-lang dependency on debugger
removed deinprogramm dependency on stepper, debugger, and htdp-langs
both still depend on test-engine tool, but only for execution
Probably apply to release branch, but needs review.
svn: r14119