Default values for all defined types

[mikaelarguedas]

• Numeric types:
  • [x] add testing for existing default values supported https://github.com/ros2/rosidl/pull/165
• Strings:
  • [x] design doc https://github.com/ros2/design/pull/110
  • [x] implementation in parser https://github.com/ros2/rosidl/commit/e43a73f28f199a356004ef1aaf2aeeeb6c9f09e1 https://github.com/ros2/rosidl/pull/205
• Primitive arrays:
  • [x] design doc https://github.com/ros2/design/pull/111
  • [x] implementation https://github.com/ros2/rosidl/pull/197
• Complex types:
  • [ ] design doc
  • [ ] implementation (parser + generators)

[mikaelarguedas]

This is currently stall based on the decision on the IDL format. Though the "primitive arrays" PR is almost ready to go. It's just missing a bit in the cpp message generation for initialization of string arrays where default strings contain escaping characters