wx.lib.flatnotebook: Patch from Andrea that implements the following:

wx.lib.flatnotebook: Patch from Andrea that implements the following:

 * A new style FNB_FF2: my intentions were to make it like Firefox 2,
   however it turned out to be an hybrid between wxAUI notebook glose
   style & FF2 ...I still think it looks OK. The main purpose for
   making it more like wxAUI is to allow applications that uses both
   to have same look and feel (or as close as it can get...);

 * Changed the behavior of the left/right rotation arrows to rotate
   single tab at a time and not bulk of tabs;

 * Updated the demo module.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45521 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775