Make the diff parser return mergeinfo data contained in a diff.
This requires a special parsing step for pretty-printed mergeinfo
diff data, which is partly affected by i18n.

This is a prerequisite for eventual svn:mergeinfo support in 'svn patch',
tracked as issue #3747. However, making 'svn patch' apply mergeinfo
changes will first require making 'svn patch' mirror the results of
'svn merge' much more closely. Among other things, 'svn patch' needs
smarter handling of tree changes. E.g. copies created by a merge should
be created as copies by 'svn patch'. Currently, 'svn patch' transforms
copies into additions. It's unclear to what extent 'svn patch' could
emulate 'svn merge' because the unidiff format and it's various extensions
are quite different to Subversion's internal merge editor.

A grumpier type of SVN developer might even insinuate that svn:mergeinfo
is far from useful in the context of 'svn patch'. However, making the
diff parser return mergeinfo data should not contradict this notion,
nor should it make future research into perfect patch strategies impossible.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1600096 13f79535-47bb-0310-9956-ffa450edef68