0025213: Visualization, TKOpenGl - do not use deprecated built-ins in GLSL shaders

Inherit NCollection_Buffer from Standard_Transient, do not use incomplete NCollection_Handle.

OpenGl_Context, add methods ActiveProgram(),BindProgram()
to manage currently active GLSL program.
Add method ::ToUseVbo().

OpenGl_ShaderProgram, setup locations of pre-defined vertex attributes
occVertex, occNormal, occTexCoord, occColor before linkage.
Remove methods OpenGl_ShaderProgram::Bind(), ::BindWithVariables()
and ::Unbind() - OpenGl_Context::BindProgram() should be used instead.

Introduce class OpenGl_VertexBufferCompat, which emulates VBO
behavior on systems without VBO (compatibility with broken OpenGL drivers on Windows).

OpenGl_PrimitiveArray - use OpenGl_VertexBufferCompat when VBO is unavailable,
remove duplicated code. Use OpenGl_VertexBuffer::HasNormalAttribute()
method to activate lighting.

OpenGl_Text - use OpenGl_VertexBufferCompat, eliminate duplicated code.

Changes in OpenGl_VertexBuffer, drop methods BindFixed()/UnbindFixed().
Superseded by new methods BindAllAttributes()/UnbindAllAttributes()
which handle active GLSL program, when it is set.

src/OpenGl/OpenGl_ShaderManager.cxx

@@ -34,7 +34,6 @@ IMPLEMENT_STANDARD_RTTIEXT(OpenGl_ShaderManager, Standard_Transient)
 // =======================================================================
 OpenGl_ShaderManager::OpenGl_ShaderManager (OpenGl_Context* theContext)
 : myContext  (theContext),
-  myIsPP     (Standard_False),
   myLastView (NULL)
 {
   //