TML - Add styling (similar to css)

[Kiyoshika]

Could be convenient to have styling, but instead of having a separate <style> tag we may do something directly in <script>. Something like: (note that all of the attribute names in the class must be publicly accessible and named exactly the same as the original attributes)

<tml>
  <text class=myTextClass>hey</text>
  <text class=myTextClass>yo</text>

  <script>
    class myTextClass {
      public bool bold = true;
      public colour fg = colours.yellow;
      public colour bg = colours.blue;
      public bool newline = false;
    };
  </script>
</tml>

would be equivalent to

<tml>
  <text bold=true fg=yellow bg=blue newline=false>hey</text>
  <text bold=true fg=yellow bg=blue newline=false>yo</text>
</tml>

It may not be a big deal in this small example, but for larger amounts of generalizable elements it may come in handy.