Define curried data constructor via Quark.Partial.defpartial

`defpartial/2`   is   called    with   `args_without_defaults`   because
`defpartial/2` is  implemented using `defcurry/2` which  would pass args
with defaults to an anonymous function, but:

```elixir
== Compilation error in file lib/algae/tree/rose.ex ==
** (CompileError) lib/algae/tree/rose.ex:34: anonymous functions cannot have optional ar
guments
    (stdlib) lists.erl:1354: :lists.mapfoldl/3
    (elixir) src/elixir_fn.erl:19: :elixir_fn.expand/3
    lib/algae/tree/rose.ex:34: (module)
```

On the other hand,  it doesn't seem to be logical  to have defaults when
currying anyway:

```elixir
defmodule Person do
  defdata do
    name :: string
    age  :: integer
  end
end

Person.new_partial.("lofa")
```

I  would expect  the last  expression to  return a  function instead  of
`%Person{name: "lofa", age: 0}`.

lib/algae/internal.ex

@@ -10,17 +10,36 @@ defmodule Algae.Internal do
   def data_ast(lines, %{aliases: _} = caller) when is_list(lines) do
     {field_values, field_types, specs, args, defaults} = module_elements(lines, caller)
 
+    arg_count = Enum.count(args)
+
+    overridables =
+      Enum.map(0..arg_count, &({:new_partial, &1}))
+      ++ [new: arg_count]
+    # More verbose, but clearer.
+    # for arity <- 0..Enum.count(args) do
+    #   {:new, arity}
+    # end
+
+    args_without_defaults =
+      Enum.map(args, fn({:\\, [], [stripped, _]}) -> stripped end)
+
     quote do
+      use Quark
+
       @type t :: %__MODULE__{unquote_splicing(field_types)}
       defstruct unquote(field_values)
 
+      defpartial new_partial(unquote_splicing(args_without_defaults)) do
+        struct(__MODULE__, unquote(defaults))
+      end
+
       @doc "Positional constructor, with args in the same order as they were defined in"
       @spec new(unquote_splicing(specs)) :: t()
       def new(unquote_splicing(args)) do
         struct(__MODULE__, unquote(defaults))
       end
 
-      defoverridable [new: unquote(Enum.count(args))]
+      defoverridable unquote(overridables)
     end
   end