for teaching purposes only
limited to a microscopic fragment of Python for the moment

          * Nested comments are supported
          * Add a special exception for the (*) token

[trywhy3] Allow one to compile trywhy3 with debugging information and source map file by passing DEBUGJS=yes to make.

- Define set with create (and constrained a benign mistake on axioms)
- s/FloatMatrix/Matrix

to handle non-square matrices

This patch solves a problem on the order of the generation of new
declarations by intro_projections_counterexmp. The problem came from
the combination of Trans.on_tagged_ls and Trans.decl. The former was used
to know each projection function in advance and the latter would
introduce new declarations directly at the definition of the decl being
analysed sometimes using projections functions before they are defined.

This patch makes intro_projections_counterexmp.ml adds declarations only
at the end of the task. So we are sure that any meta is really defined
before.

* src/transform/intro_projections_counterexmp.ml
 (introduce_constant): Minor clarification.
 (projections_for_term): Replacing append with proper symbol. Also adding
  already computed list of declaration to the output.
 (introduce_projs): Removing already defined declarations from the set of
  declaration we will add.
 (build_projections_map): The order of elements is irrelevant so
  it is faster to use cons instead of append.
 (meta_transform2): Add declarations created by f at the end of the task.
 (encapsulate): Compose meta_transform2 and introduce_projs.
 (commented meta_transform2): Request for a fold able to do what is
  described.

The one liner is missing because we did not project value of array
elements in intro_projections_counterexmp. I changed the whole algorithm
of projections to allow projecting values of multidim array. Also,
moved local functions outside the main function. Added some trivial
helping functions.

* intro_projections_counterexmp
 (detect_map_types): Takes a type and return the list of successive types
  in the map and the return type. On map int (map int int) returns
  ([int; int], int).
 (last_type): Takes a list of proj_functions and returns the return type
  of the last projections_function that will be applied.
 (recreate_types): Recreates the type of the map with projected return
  type.
 (create_index_list): Returns a list of new well typed symbol for
  application in the axiom.
 (recreate_term_applications): Apply array to indices.
 (list_projection_until_base_type): Returns the list of all possible
  list of proj_functions applied to it.
 (projections_for_term): Changed the map part almost completely. We do
  not call this function recursively but we used other functions to get
  the recursive behavior.

To install the Why3-related Vim files, just create a symbolic link:
  ln -s "$(why3 --print-datadir)/vim" ~/.vim/bundle/why3

Thanks to Johanness Kanig for the suggestion.