WIP: Add a Context object

[kskyten]

I tried to add a Context object as per #20, but ran into some issues. For some reason the context object seems to get inserted into the generated code. This is what I get:

julia> using Py2Jl.ASTGen: Context, to_ast

julia> using Py2Jl.Process: process

julia> xp = process("""
       def foo(x):
           x + 1
       """)
Dict{Symbol,Any} with 2 entries:
  :class => "Module"
  :body  => Dict{Symbol,Any}[Dict(:name=>"foo",:args=>Dict{Symbol,Any}(:kwarg=>nothing,:args=>Dict{Symbol,Any}[Dict(:…

julia> to_ast(Context(nothing, nothing), xp)
:(module filename
  Py2Jl.ASTGen.var"##λ#253#9"{Nothing}(nothing)
  begin
      function foo(x)
          begin
              Py2Jl.ASTGen.var"##λ#253#9"{Nothing}(nothing)
              begin
                  (+)(x, 1)
                  nothing
              end
          end
      end
      nothing
  end
  end)

I don't fully understand what gather, tag_loc and trans_block are doing. Also I didn't find what the definition for the <| operator inside the _apply pattern function is. I see how you are using the Record pattern to do a kind of a destructuring bind on the keys of a dictionary, but I don't understand how the definition works from the MLStyle docs.

[thautwarm]

You are correct, and now I don't think the functions confusing you are good to keep. Instead of making this PR, I prefer to talk with you about how to evaluate generated julia code in given module. This is the approach I'd prefer.