Block binding: fix useless variable rename for some VAR scoped declarations

Closes #1323
Block Binding: hoist function declaration in block to beginning of block

Closes #1304
Block Binding: use orignal name where possible

Closes #1274
fix export default parsing
Enable block binding by default

Issue #1277
Fix repl after #1331 broke it.

Fixes #1351.

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1353

Closes #1353, closes #1351.
Deps need only ModuleSymbol info

Part of a refactoring to use Compiler in Loader.

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1349

Closes #1349.
Cleanup

Fixes comments in BlockBindingTransformer

Fixes FindUnusedImports (it broke due to compiler changes)

Remove unused imports
Manual update to verions 0.0.64 and ignore compat errors

TBR=@arv

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1357

Closes #1357.
0.0.65