Removing stdint.h dependency from the public API to avoid conflicts with other libraries.

Removing stdint.h dependency from the public API to avoid conflicts with other libraries.
Cleaned up aiTexture.h, AssimpPCH.h and MaterialSystem.h.
Updated child apps & makefiles to reflect these changes.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@385 67173fc5-114c-0410-ac8e-9d2fd5bffc1f