It is now the user's job to track the lifetime of a glutil.Image
relative to a (currently implicit, soon to be explicit) GL context.
This is an attempt to move glutil.Image closer to the model for
buffers and textures in shiny. Long-term, I would like to adopt that
model, and this is a step in that direction. It also makes the
introduction of *gl.Context possible, so this is a pre-req for
cl/13431.
Change-Id: I8e6855211b3e67c97d5831c5c4e443e857c83d50
Reviewed-on: https://go-review.googlesource.com/14795
Reviewed-by: Nigel Tao <nigeltao@golang.org>
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