After minor modifications to pyratemp, it certainly does the job.
What it **does NOT** do:
* multiple outputs per template/command invocation
* NICE embedding of code (like GSL can)
It will do the job nonetheless, but mako might be worth a look
As GSL failed in my first attempt to get the example program going,
it might be better to try something else before too much time is spend.
Fortunately, pyratemp **seems** to be something usable, and even if not,
it might be possible to make it usable as it's just a 'simple'
python script that I might be able to understand, if need be.
