close #978

close #753

Update SLE12-SP2-btrfs-example.conf

Fixed typo in BACKUP_PROG_INCLUDE:
"var/lib/machines/*" must be "/var/lib/machines/*"

Fixed suse spelling typos,
see #1004

…ue974

Better documentation that "BACKUP_TYPE=incremental"
implements only support for one full backup plus one
single incremental backup so that currently it is actually
support for a differential backup, see
#974

Additionally enhanced the general comment in default.conf
about how to use our variable types, in particular added
info about ternary semantics that is when both the is_true
and the is_false functions are used for a variable because
then "tertium datur" when the variable has neither an explicit
true value nor an explicit false value (e.g. when it is unset,
empty, or has an arbitrary other value like "foo").

…_check_rsync_protocol_version.sh) that had been accidentally rewritten as regular files in previous commit

…x-and-Recover_issue1008

Corrected misspelled forms to Relax-and-Recover