* Apply Namer to Dart.
- Also refactor idl_gen_dart a bit
- to use more const and references
- out parameters should be the last argument
* Add keyword test
* minor fixes
* fix merge
* extra 's'
* move dart keyord into dart dir
* Address comments
* Use $ for escaping keywords
* Outparameters for namespace_map
* Escape dollar in toString
* Escape dollar in toString2
* Use UpperCamelCase for types and variants
* try to fix ToString
* namer Type fixes
* Remove path prefixing in imports
* gen code
Co-authored-by: Casper Neo <cneo@google.com>