Allow svnlog2ul.sh to run on the current working copy

And from the root directory instead of having to cd to util/svnlog2ul
Original author: John Ralls <jralls@ceridwen.us>

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash-docs/trunk@22984 57a11ea4-9604-0410-9ed3-97b8803252fd