Refactor placeholder parser

This is to allow yield and await everywhere.

Also, restructure the code to reduce code size.
promisified recursiveModuleCompileToSingleFile

process.exit and console errors happen now in command.js

Fixes #1267
Re-support type="text/traceur" to enable global semantics for scripts

...tics for scripts

	Fixes #822

	The difference between scripts with type="module" and "text/traceur" is that the "text/traceur" script's globals will be global to all the other scripts, just like regular es5 script tags.

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1033

Closes #1033, closes #822.
Rewrite BlockBindingTransfomer for better performance
Add missing copyright headers
Change parser to disallow import in Script by default

Also, update the placeholder parser to make parseStatement actually
start at ModuleItem (which in turn includes StatementListItem)

Fixes #1272
Remove async Compiler functions

Rename API functions with conventional names:
stringToTree -> parse
treeToTree -> transform
treeToString -> write

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1278

Closes #1278.
Fix arguments and this transforming for FnExtractAbruptCompletions
Hoist variable outside function in FnExtractAbruptCompletions
Add test for detecting Functions as Block Binding for BlockBindingTransformer
Set moduleName when modules option is 'inline'

Fixes #1282

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1285

Closes #1285, closes #1282.
Set.prototype.add no longer returns its map
map.prototype.delete return value
Implement MultipleErrors extends Error as a throwable type for compiler

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1283

Closes #1283.
Depend upon es6-module-loader npm.
Remove Loader, use Reflect.Loader from es6-module-loader instead.
Rename make var SRC to MODULES_SRC
Attach types to each input file in the Makefile
Compile es6-module-loader.js into traceur.js.
Load system.js from es6-module-loader node_module

Reorder build to boot Promises and still get them in System registry.

InlineLoaderHooks -> InlineTraceurLoader.

Create LoaderInterface

Rework modulestore

Combine node/web System modules and initialize with bootloader _loader.

Remove Loader hooks in favor of extending Loaders
Rename new TraceurLoader to TraceurLoader2 and resurect TraceurLoader
Partial sync to master