Minor build system and testing improvements and bug fixes

Minor build system and testing improvements and bug fixes

Bug fixes

• #455: A shell script stack implementation was failing for certain bash
  versions, most notably versions provided by default on CentOS 6
• #452: Coarray extension/convenience module was installed in the wrong place
  due to typo
• A typo was causing a CMake error when MPI was missing and has been fixed
• An issue where the build script was trying to query version information from
  dependencies with the wrong flag has been fixed
• #461: Some tests were failing if the build system detected < 3 cores
  available because the tests require more than 2 images and they were being
  run anyway, without oversubscription.
• #457: A problem with CMake caching was causing some system introspection
  relevant to windows systems to fail, and has now been resolved

Enhancements

• #267: CMake can now use properties (on test target executables) to specify
  the minimum number of images. This ensures ctest/make check/make test
  will oversubscribe these tests appropriately when not enough cores are
  avaialable.
• #413: Add a make dist target to help OpenCoarrays developers produce
  release assets: source tarballs, SHA 256 checksums and PGP signatures
  if GPG is setup locally

Installation

Please see the installation instructions for more details on how to build and install this version of OpenCoarrays

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