Handle example code snippets with MakeExamples() class

- add script/meta_examples.py
- copy examples from python-api docstrings
- move color and colorscale examples from meta_shortcuts.py
Update meta and meta shortcuts modules

- make ValTypes and RequiredCond classes
- add support for MakeExamples class
- add 'name' in graph obj *stuff*
  (e.g. to handle: Scatter in python, but scatter otherwise)
- remove .format() (now done in run.py)
- rename 'meta' to 'keymeta'
Update run.py

- add formatting function to handle all language-dependent vocabulary
- add *retrieve* function to handle language-dependent MakeExamples instances
modif tests for new json structure