todo notes
fix copyright years
gitignore tags file
adapt to Elixir 0.14.x

Affected area is implementation and syntax of HeapMap.
There's no more recordp.method() -like syntax in Elixir.
Now the HeapMap usage went functional using |> operators.
There was no need to use struct - this is simple impl hiding,
also no need to use Access protocol, doesn't get that much clarity.
|> travis