the text implementation to provide better speed, especially by using the
alignement to screen option.
Deprecated the Text::setFontSize(,) method, which is now being replaced
by setFontResolution(,)
Fixed typos in Texture*.cpp.
Removed old deprecated methods from osg headers.
leaving it up to the Viewer to specify the mode (which by default is MultiThreaded).
Added a check for the presence of osgParticle systems so that threading is
disabled in this case.
