all: start stable branch light0.1.y

This branch will receive only bugfixes, no new features.
server: fix refcounting
infra: fix string allocation in mars_readlink()
proc: fix too long string allocation
infra: make string allocation fully dynamic
infra: fix mem error messages
client: fix error propagation
aio: fix races in EOF computation
light: maintain limiter rates even when switched off
light: don't disturb fetch infos when switched off
light: fix annoying replay error message
marsadm: show IP only with --verbose
marsadm: fix usage
brick_mem: improve debugging
infra: improve callback debugging
all: improve checking of callback chain
doc: update
userspace: add bugfix for Debian udev rules

Patch received from Jörg Mann by email.

Some Debian versions seem to have typos in their udev rules.
As a consequence, /dev/mars/mydata does not disappear when
leaving primary state.

Other consequences might also exist. In an unreproduced case the
/dev/mars/ object was unlinked while the mount was continuously
active, without causing any harm to operations (besides that
xfs_growfs did not work, which led to the discovery of the
mysterious situation).

Probably the udev userspace may require further fixes.

Fortunately, udev-less systems (as those used by me for testing) are
not affected.
monitoring: update
all: release light0.1stable01