GL_EXT_clear_texture
http://www.opengl.org/registry/specs/EXT/clear_texture.txt
GL_EXT_clear_texture

	void glClearTexImageEXT (GLuint texture, GLint level, GLenum format, GLenum type, const void *data)
	void glClearTexSubImageEXT (GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, const void *data)