GL_ARB_clear_texture
http://www.opengl.org/registry/specs/gl/ARB/clear_texture.txt
GL_ARB_clear_texture
	GL_CLEAR_TEXTURE 0x9365
	void glClearTexImage (GLuint texture, GLint level, GLenum format, GLenum type, const GLvoid* data)
	void glClearTexSubImage (GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, const GLvoid* data)