Moved osgText across to create GL_ALPHA textures instead of GL_LUMINANCE_ALPHA

include/osgText/Font

@@ -19,6 +19,7 @@
 #include <osg/Texture2D>
 #include <osg/StateSet>
 #include <osg/buffered_value>
+#include <osg/TexEnv>
 
 #include <osgText/Export>
 
@@ -137,6 +138,8 @@ protected:
     osg::Texture::FilterMode        _minFilterHint;
     osg::Texture::FilterMode        _magFilterHint;
     
+    osg::ref_ptr<osg::TexEnv >      _texEnv;
+    
     osg::ref_ptr<FontImplementation> _implementation;