Add \scan_stop: after the setup arg of tl_rescan

I'm not sure about this one, but the new tl_set_from_file functions
do that, and there is indeed a risk that the assignments in the
setup argument of tl_rescan might end with \someint=123 not properly
terminated.  I'm happy to remove it.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5195 de43f980-851b-0410-b2f7-c40aca1f87e0
Simplify implementation of tl_set_from_file

and incidentally fix a minor bug (if a file was surrounded by
a brace group, with no endlinechar at the end, then those
braces were lost).


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5196 de43f980-851b-0410-b2f7-c40aca1f87e0