Merge remote-tracking branch 'origin/maint-0.2.5'

changes/bufferevent_compilation

changes/bug8387

changes/further-12184-diagnostic

configure.ac

src/or/circuitbuild.c

src/or/circuituse.c

src/or/circuituse.h

src/or/connection.c

src/or/control.c

src/or/main.c

src/or/router.c