matlab: support Octave 4.0.0

matlab: support Octave 4.0.0

- Workarounds for Octave 4.0.0:
    - no containers.Map yet so use new Dict
      structure when running under Octave.
    - weird error when +FOO/ directory and FOO.m file both exist so
      rename types.m to type_utils.m
    - no getReport so implement custom stack printer
    - workaround weird issue that happens when a class initializer is
      called with the first argument of the same class as per
      Env(outer, ...). The class is not properly initialized. So for
      now, wrap the outer in a cell as Env({outer}, ...)
    - missing MException object types so when in Octave, use a global
      variable to store the error object.
    - missing native2unicode so just use 0xff character for keyword
      prefix.
    - workaround some function calling/passing differences. For
      example, the "@" anonymous function symbol does not seem to work
      for conveying an existing function but only for defininign a new
      one. E.g. this works:
          @(a,b) a+b
      but this doesn't
          @my_adder_fn.
      so just do this:
          @(a,b) my_adder_fn(a,b)

- Add Dockerfile with Octave

- Active Travis for matlab implementation using Octave