Single Hpp File - v.8.1.0

See the v.8.1.0 milestone for the full list of changes.

• Breaking changes
  • None
• New features
  • Added ability to detect ApprovalTests.cpp version in code: see Version detection (#40)
• Bug fixes
  • Relaxed the static_assert check on __FILE__ to stop it wrongly triggering in Cygwin builds that don't define _WIN32 (#92)
  • Fixed inability to use project as sub-module on Windows due to long filenames - by shortening the names of some files and folders in the tests. (#38)
• Other changes
  • Include __FILE__ value in static_assert message, to aid diagnosis
  • Implement check for broken links in documentation (#26)
  • Fixed some broken links in documentation (#26)