Zevo support.
fix for filesystem expansion when using '//'
README updates
going back to standard /bin/sh (bash 3.x on macosx)
comments update
mktemp on macosx uses some .Xs by default, which is not the case on linux
issue #8 should be solved by this patch

all filesystems with snapdir=visible and canmount=on are traversed for
snapshots going to be removed and umount -f is called.

on linux, on /proc/mounts such mounted snapshots are visible (not
listed with 'mount'), but under macosx no proc exists, 'mount' again
does not list them so umount -f is called with no mercy for all
specific combination of fs and snapname  (but should not cause any
problems).

there is no specific logic to utilize /proc/mount on linux, same
approach is taken.
detection of system (Linux/Darwin). proper detection of mounted snapshots prior to umount.

detection of system applies for local and remote operations. should run
on linux and macosx with no modifications in the code.
error return codes renumbering, parameter checking for --send
general cleanup, quotations updates etc
bug fix (wrong recursive filesystem list expansion)

in case of empty filesystem list going for recursive snapshot all
filesystems have been processed
bug fix (snapshot list created for destroy in case of incremental send through replication)
Revert "bug fix (snapshot list created for destroy in case of incremental send through replication)"

This reverts commit 8b155cf4da071b79fc4eee034f87c0cdb16769b9.
Revert "bug fix (wrong recursive filesystem list expansion)"

This reverts commit d6c05fb8f4db695ec01ea59c1edb4b7d428db98d.
bug fix (wrong recursive filesystem list expansion)

in case of empty filesystem list going for recursive snapshot all
filesystems have been processed
better snapshot consistency testing during --send-full and -R
cosmetic bug which showed filesystem added for regular snapshot as recursive
missing quotations, under bash ok, under dash critical
rewritten bash (non portable) code into standard posix

tested on dash 057
fixes