Bump to 8.5.15 for release.
changes
Favor timeline over ChangeLog; also 'make dist'
Added note to ChangeLog pointing to the fossil timeline for better logging.
merge 8.5; update changes
merge release
workaround for mingw bug [http://comments.gmane.org/gmane.comp.gnu.mingw.user/41724]
workaround for mingw bug [http://comments.gmane.org/gmane.comp.gnu.mingw.user/41724]