Btrfs progs release 3.18.1

Hi,

this is a followup that updates documentation, contains a few fixes from coverity reports and a few recent small-sized fixes.

There's a pile of patches that reorder subcommands in the manpages. I did not send them to the mailinglist as they're pretty trivial and would be just noise. Similar holds for the coverity fixes, they're mostly straightforward.

Near future plans. There are several patchsets pending, I'm not yet decided in which order I'll merge them, but would like to get the core changes and some UI updates in before I branch off 3.19.x. Then switch build system to autotools and merge the rest.

Tarballs: https://www.kernel.org/pub/linux/kernel/people/kdave/btrfs-progs/
Git: git://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git

david