Use container size as reference

[ivmartel]

The current code exposes a fitToWindow options to fit the size of the viewer to the containing window. This should be the responsibility of the calling app: the viewer should fit to the container div and the app set the div size to the window one or not. In this case the option would not be needed any more and could be removed.

This can be useful in a full screen scenario where the viewer is part of a page at a reduced size and provides a full screen option where you want it to be as wide as possible.