Merge branch 'master' into ng/master

Merge branch 'master' into ng/master

* master:
  options: consistently use return statuses to report errors (more)
  options: try to report as much errors as possible
  warns: don't tell AM_PROG_MKDIR_P is going to be removed
  refactor: fix few "inverted boolean" usages
  options: better name for an internal function
  options: more consistency in use of return statuses to report errors
  options: tiny simplification in dealing with erroneous opts
  options: consistently use return statuses to report errors
  options: re-enable some sanity checks
  THANKS: update Eric Blake's e-mail address
  NEWS: typofix
  dist: remove support for shar and tarZ formats
  news: document new 'subdir-objects' warning
  PLANS: one minor fixlet (mostly cosmetic)
  PLANS: we have already dropped support for split info files in master
  NEWS: fix a reference to Automake 1.14 where Automake 2.0 was intended
  PLANS: fix reference to non-existent 'next' branch
  PLANS: fix botched version reference
  maintcheck: fix two references to old location of aclocal and automake
  dist: deprecated shar and tar+compress formats

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>