Remove inlineAndCompileSync and its use,  require.js.

The sync compile was only used for two test files.
These tests are now compiled explicitly in the Makefile.
The .traceur.js pattern for triggering compilation now is .generated.js;
the source files are in test/unit/es6.

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/604

Closes #604.
Fixup runner.html for .traceur.js to gnerated.js.

Drive-by: remove unused options code

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/606

Closes #606.
Safer build: copy src/node to build/node.

Add traceur-build that runs out of build/ and thus uses build/node/*.js.
Copy current src/node to build/node-save, restore last-good src/node,
copy to build/node, restore src/node. This reduces ways that src/node
changes can be lost by build shenanigans.

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/607

Closes #607.
Use LoaderHooks for customization in src/node.

Move fileLoader from Loader to LoaderHooks; use fetch() per spec.
Pass fileLoader as arg to LoaderHooks, not property-set on Loader.
Remove src/node operations on InternalLoader, now extends LoaderHooks.
Remove loadSync() and friends
Move Loader evalCodeUnit to LoaderHooks.evaluateModuleBody (per spec-ish)
Driveby: correct WebPageTranscoder to succeed if run() after DOMContentLoaded.

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/608

Closes #608.
Makefile rules for build/node.

The files in build/node are checked out from a previous git commit,
ie they are 'known good' versions of src/node files. Added rules to create or update
build/node when src/node/* changes. Removed the deletion of build/node upon success in
the build and added build/node to .gitignore instead.

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/610

Closes #610.
Minimal Loader API.

Close to the spec: import(url, callback, errback),
  module(source, options, callback, errback).
Not in spec: loadAsScript(url, callback, errback),
  script(source, name, callback, errback).
Other functions removed

Review URL: https://github.com/google/traceur-compiler/pull/615

Closes #615.