use strdup, simplify free

[Seth Arnold]

When I read the scopes tutorial I thought it was complicated and thought
some of the extra work that was being done manually contributed to the
complication.

This untested patch removes the non-NULL checks before free(3) calls which
isn't necessary and also replaces manual memory allocation with strdup()
when duplicating many strings. I believe the end result is easier to read.

Please consider applying this patch to the tutorial.

Thanks

[Daniel Holbach (dholbach)]

It looks like the code in question does not exist anymore.