ensure framebuffer textures are detached and deleted, avoid leaving framebuffers bound when not needed
* render: avoid calling glDeleteProgram on no program
its safe to do so but it adds a bunch of unnecessery lines in apitrace
when tracing. if guard it and return early.
* opengl: ensure texture and buffers are unbound
ensure bound buffers are unbound after use, also detach textures from
framebuffer before deleting it otherwise it will become dangling and
essentially leak.
