Valve KeyValues Text File Format (.vdf) decoder

Pure Elixir Valve KeyValues Text File Format decoder.

Using

VDF.decode(~s/a b c {"d" {"e" "f"}}/)
# {:ok, %{"a" => "b", "c" => %{"d" => %{"e" => "f"}}}}

VDF.decode("a b \n{c d}")
# {:error, %VDF.Error{message: "unexpected open bracket (2:1)"}}