Finish gf wrapping

- clean old.
- clean gf_desc.py
gf : clean test output

- remove the tt group, we can not save a tail independantly any more,
  makes little sense.
lattice : python wrapper
Change implementation of random_generator & python wrapper.

- Use a new buffered_function to replace the complicated generator code from ALPS.
- Clean the implementation of the random_generator
- update the documentation
- update to the new python wrapper (could not be done with the previous
  version, because of lack of move constructor).
wrapper: add static methods

- is_static= True to wrap a static method.
wrapper : correct namespace in enum in converters

- the absolute path was missing for the value of the enum.
fixes in wrap_generator, parameters, h5 for strings

- string size in h5. Add +1 (or empty string is wrong).
- parameters : modified flags from python
- minor corrections in wrapper
Remove Cython & prepare wrapper for applis.

- removed cython : macro, detection, pxd, etc...
- adapt wrapper tools for external applis.
- cleaned doc for cython
wrapper : remove the need of default constructor

- change the constructor wrapper.
- in the new method, leave the pointer _c to NULL.
- in the init, allocate it.
- It seems ok to leave the object in this non initialized state,
  but that is not so clear from the doc.
  Added check for this pointer == NULL in converters.
wrapper: add use_module

- a module can use the converters used by another
  with the use_module('A') command.
  In which case :
    - the generate converter header for A will be included.
    - the header, at the top, now contains a simple list of all
      wrapped types, which is then included in the wrapped_types
      of the module for proper code generation.
- simplify the code generation : just generate_code.
- all arguments are analyzed from sys.argv at the import of the
  wrap_generator module. In any case, the xx_desc.py will be called from the corresponding
  cmake command, hence with the right arguments.
- Added a dependencies in my_module_B of wrap_test to show how to make
  the dependencies in the cmake file, if needed.
wrapper: add release_GIL_and_enable_signal option.

- Add to the wrapper generator (add_method) the release_GIL_and_enable_signal option which :

   - release the GIL
   - save the python signal handler
   - enable the C++ triqs signal handler instead.
   - undo all of this after the code runs, or in a case of exception.
   - used python include, ceval.h, line 72 comments and below.

- reworked the triqs::signal_handler.
  simple C like function, no object (no need).
  start, stop, received, cf header file.

- clean the call_back.cpp : only place using the signal directly
  (qmc uses the callback).
  in particular, remove the old BOOST CHRONO, since
  the std::chrono works fine on platforms we use now.
gf: triqs_auto_assign for gf_view

g[k][om] : missing an overload for views
move wrap_test to test/pytriqs