Refactor grammar and unify base_expr into max_expr
Refactor grammar and unify base_expr into max_expr

joshprice/elixir,kimshrier/elixir,gfvcastro/elixir,lexmag/elixir,beedub/elixir,pedrosnk/elixir,antipax/elixir,kelvinst/elixir,pedrosnk/elixir,michalmuskala/elixir,lexmag/elixir,kimshrier/elixir,elixir-lang/elixir,antipax/elixir,beedub/elixir,ggcampinho/elixir,kelvinst/elixir,ggcampinho/elixir,gfvcastro/elixir