Add support to limit the amount of text lines drawn.

[daid]

I've added support to the drawText function to limit the amount of text lines drawn, as well as to skip the first X lines to draw.

This to add scrollable textboxes to my game. Example: http://daid.github.io/NightmareRL/ Press "L" to get a message log, you'll have to walk around a bit to fill it so it contains more lines then the screen. Then you can scroll the text with the up&down keys. The drawing code with this patch simply becomes: https://github.com/daid/NightmareRL/blob/gh-pages/dialog.js#L100

[ondras]

Sounds reasonable. The amount of arguments for ROT.Display.prototype.drawText is getting too large for my likings, though. Would you mind refactoring the code so that the signature would be

ROT.Display.prototype.drawText = function(x, y, text, options) {
  var opts = { maxWidth: null, maxLines: null, skipLines: 0 };

  if (typeof(options) == "number") { options = {maxWidth:options}; } // backwards compatibility 

  for (var p in options) { opts[p] = options[p]; }

   /// ... code as is now
}

?

This would also allow some potential space for future improvements of drawText (although I am personally not using it at all, rendering paragraph text via regular HTML instead).