Add koans for floats, rename to numbers koans, reposition on the list

lib/koans/06_lists.ex

@@ -1,69 +0,0 @@
-defmodule Lists do
-  use Koans
-
-  @intro "Lists"
-
-  koan "We can see what is ahead" do
-    assert List.first([1, 2, 3]) == ___
-  end
-
-  koan "Checking what's trailing is also simple" do
-    assert List.last([1, 2, 3]) == ___
-  end
-
-  koan "Lists can store anything you throw at them" do
-    assert [1, 2] ++ [:a, "b"] == ___
-  end
-
-  koan "Things can evolve" do
-    assert [1, 2, 3] -- [3] == ___
-  end
-
-  koan "Evolution can have different forms" do
-    assert List.delete([1, 2, 2, 3], 2) == ___
-  end
-
-  koan "Precision is also valued" do
-    assert List.delete_at([1, 2, 3], 1) == ___
-  end
-
-  koan "Replication is also possible" do
-    assert List.duplicate("life", 3) == ___
-  end
-
-  koan "Sometimes leveling the playing field is desired" do
-    assert List.flatten([1, [2, 3], 4, [5]]) == ___
-  end
-
-  koan "Order can also be specified for new members" do
-    assert List.insert_at([1, 2, 3], 1, 4) == ___
-  end
-
-  koan "We can replace things at specified positions" do
-    assert List.replace_at([1, 2, 3], 0, 10) == ___
-  end
-
-  koan "When a replacement cannot be found, the list remains the same" do
-    assert List.replace_at([1, 2, 3], 10, 0) == ___
-  end
-
-  koan "Order is bound by nature's laws" do
-    assert List.insert_at([1, 2, 3], 10, 4) == ___
-  end
-
-  koan "Sometimes it's faster to loop around back" do
-    assert List.insert_at([1, 2, 3], -1, 4) == ___
-  end
-
-  koan "We can also transform ourselves completely" do
-    assert List.to_tuple([1, 2, 3]) == ___
-  end
-
-  koan "Wrapping other values is a handy option" do
-    assert List.wrap("value") == ___
-  end
-
-  koan "When there is already a list do not wrap it again" do
-    assert List.wrap(["value"]) == ___
-  end
-end