contrib/*: Support the "--help" and "--version" options

contrib/*: Support the "--help" and "--version" options

Add "--help"/"-h" and "--version"/"-V" support to all contrib scripts.
Also, update scripts that used "-v" as a short option for "--version"
and use "-V" for the sake of consistency.

Additionally:

* Move version and usage messages to separate convenience functions in
  all scripts.

* Add a workaround to paccache to support "--help" and "--version". This
  should be replaced by a proper POSIX-compliant command line parser
  that supports long options in a future patch.

* Add a "$myver" variable to all scripts and use it whenever we refer to
  the program version (e.g. in version messages). Also, use the pacman
  version number everywhere instead of using a different versioning
  scheme for each contrib script. This is achieved by adding a
  "PACKAGE_VERSION" placeholder that is replaced by sed(1) when the
  script is built.

* Ensure we always return with exit status 0 if "--help" is used and
  return with exit status 1 if we display the usage message due to
  invalid arguments.

* Add "AUTOMAKE_OPTIONS = std-options" and add all scripts to
  "bin_SCRIPTS" to make `make installcheck` check that installed scripts
  actually support the "--help" and "--version" options.

Signed-off-by: Lukas Fleischer <archlinux@cryptocrack.de>
Signed-off-by: Dan McGee <dan@archlinux.org>