simple checks for desugar are up and running

- added an option to the CLI, --module-load-dir, which sets the
  base directory for loading modules.  To test desugar, which
  has its dependencies compiled in a different directory, use:

  $ node build/phase1/main-wrapper.js \
      --module-load-dir build/phase1/arr/compiler/
      src/arr/compiler/desugar.arr

- Tweaked tests in desugar (and commented some out that cause odd parse errors)
better parse error message that gets a stack trace
remove log
clean up tests
Add -check-all option to test everything required by a module

You can now run with -check-all, and all imported modules will be run as well
for their tests.  So, for example, to test the compiler's check blocks, which
hits desugar and the various ASTs, you can run:

node build/phase1/main-wrapper.js \
  --module-load-dir build/phase1/arr/compiler/ \
  -check-all src/arr/compiler/compile.arr
tweak eval for new checkers interface, and add compile.arr to makefile
Merge branch 'new-world' into new-id
fixup intermediate stage
new visitor pattern for bindings