Array dispatchers : add support for "normalize" parameter and more array data types

Hi, 

Here is a submission to support more data types and binding in OSG when using vertex attributes (standard or user defined). 

This should solve this issue : 

http://forum.openscenegraph.org/viewtopic.php?t=11267&highlight= 

(solved mine, but it is application-dependant since some data types/binding types/target attribute combinaisons are not supported by OpenGL and/or OSG) 

There are 4 classes modified, from simpler to more complex : 

1/ Drawable/Drawable.cpp : 
=> more extensions are loaded 

2/ State/State.cpp : 
=> all VBO binding methods like "setVertexPointer" or "setNormalPointer" have a new parameter to select if the array is bound as a "normalized" array. This parameter is set by default to "GL_FALSE", except for colors, so they works just as before 

3/ ArrayDispatcher/ArrayDispatcher.cpp : 
=> the array dispatchers are now registered in the "_attributeDispatchList" vector as a pair : a function pointer for "unormalized" dispatch and a function pointer for "normalized" dispatch 

=> all methods which return an arrayDispatcher have a new parameter : "normalized" which is set to default to "GL_FALSE", except for colors, so they works just as before 

4/ Geometry.cpp : 
=> the drawImplementation now take cares of the "normalized" for all array data. 


In conclusion : 
- BIND_OVERALL should now work in all situations where it should work (I mean supported by OpenGL and supported by OSG) 
- when using byte, short or integer data arrays, the "normalized" parameter should be applied correctly