The zoomed tiles now perfectly match the new ones that are about
to be received from the server.
The zooming factor is again exponentail (1.2) instead of linear.
TODO: when the window size modifies the gets paned out of the bounds
The "controls" div holds map controls suchs as the Zoom button and
it's separated from the map in order to have the controls on the top
of the page all the time.
The "document-container" div is the actual display of the document, is
what the user sees and it should be no larger than the screen size.
The "map" div is the actual document and it has the document's size
and width, this being inside the smaller "document-container" will
cause the content to overflow, creating scrollbars
