Move ad-hoc CodeUnit properties into .data object

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/601

Closes #601.
Refactor Loader to not touch ModuleSymbol; better API

Propagate to ModuleVisitor family.
Rename 'module' to 'moduleSymbol' when referencing ModuleSymbol objects.

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/602

Closes #602.
Makefile: keep node/src, build test-list first, test wiki.

When saving node/src during build, cp rather than mv. That way the
working set is ok if git checkout aborts.
Build test/test-list first so test/runner.html works even if the build fails.
Add wiki as test dependency, so 'make test' builds everything.

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/603

Closes #603.