infra: fix forgotten locking
light: fix potential endless loop
all: fix potential buffer overflows, use vscnprintf()
light: fix string memleak
infra: fix readlink() for very long paths
infra: fix removal of stale directories
light: fix potential race on deletions
infra: fix/remove buggy d_{name,path}len

In rare cases, this could lead to buffer overflows.
Replace buggy concept from the prototype phase with more
robust (although slightly less performant) code.
light: fix marker check

The old code was not portable across changes of CL_*
marsadm: fix fake_versionlink()

Always fake two versionslinks instead of one.
marsadm: disallow intended primary switch when secondaries are syncing
light: fix logfile fetch from multiple peers
light: fix peer preferences, use connect-* links
marsadm: prevent only _new_ split brains
marsadm: fix leave-resource
marsadm: fix transitive closure for log_purge_res()
marsadm: fix recursion depth of _get_common_ancestor()
marsadm: fix split brain detection
marsadm: fix warning
all: fix inconsistent terminology apply->replay

In most cases, "replay" was already used. So it is easier
to switch the rare "apply" wording to "replay" everywhere (hopefully).