fix direct delete touch object without use release crash bug;

I.
I want use touch->retain() to retain touch information in touch handle.
But it always crash if I do this.
Finally I found there is direct delete touch object in CCEGLViewProtocol:: handleTouchesOfEndOrCancel .
It's works for me with replace delete to release() .
Please check if this is correct.
Thanks.

II.
use Configuration::getInstance()->supportsShareableVAO() in place of CC_TEXTURE_ATLAS_USE_VAO.

III.
fix GL_EXT_discard_framebuffer always disable in EAGLView.mm.