Move old benchmarks out of the way
Add new benchmark tests and Grunt runner
Depend on new parser
Refactor compiler to use new parser and AST

This is a major refactor which moves things into separate ES6 modules, and completely refactors the compiler to work with the new parser and AST format.

This also brings this package in line with the ICU message format "spec".
Update contributors in package.json
Build
Remove old benchmark tests
Organize benchmark tests
Update intl-messageformat-parser to fix empty string message parsing
Build
Update tests for new parser and AST format.