- extract MaterialHelper and move all of its members to aiMaterial in /include.

- pull in IOhannes' patch to set the gcc default visibility for all symbols to NO and to mark ASSIMP_API with __attribute__ ((visibility("default"))).
- drop unneeded ASSIMP_API from most internal classes in /code, we just need to keep some exports on Windows to keep AssimpView alive.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@1066 67173fc5-114c-0410-ac8e-9d2fd5bffc1f

code/TargetAnimation.h

@@ -54,7 +54,7 @@ namespace Assimp	{
  *  Missing tracks are interpolated. This is a helper class for
  *  TargetAnimationHelper, but it can be freely used for other purposes.
 */
-class ASSIMP_API KeyIterator
+class KeyIterator
 {
 public:
 
@@ -126,7 +126,7 @@ private:
  * channel for the camera/spot light itself and a separate position
  * animation channels specifying the position of the camera/spot light
  * look-at target */
-class ASSIMP_API TargetAnimationHelper
+class TargetAnimationHelper
 {
 public: