Support Windows/MSVC

[jimporter]

This will probably only work on MSVC 2015, but we'll also need to remove some of the POSIX code (mainly fork) and replace it with Windows-specific functions.

There are also a bunch of issues with MSVC's C++14 support, some of which can probably be worked around:

• [x] Header-only mettle
  • [x] constexpr issues
  • [x] std::move isn't marked constexpr
  • [x] std::max isn't marked constexpr, and yet it compiles (wrongly) as a template parameter
  • [x] "Optional" constexpr on templates isn't supported
  • [x] No support for expression SFINAE (breaks dispatch of output functions)
  • [x] C2797 "list initialization inside member initializer list or non-static data member initializer is not implemented" (see mettle::test_caller_sub_base); this is planned to be fixed in 2015 RTM
  • [x] C3779 "a function that returns 'auto' cannot be used before it is defined" (see wrap_test functions)
  • [x] Disable the death tests (they use fork)
  • [x] Windows version of type_name
• [x] Full mettle jacket
  • [x] Port subprocess_test_runner
  • [x] Alternative to forking each test function
  • [x] Support process grouping
  • [x] Support timeouts
  • [x] Support DLL builds
  • [x] Add colored output
  • [x] Alternative to mettle's child process creation
  • [x] Windows version of the death tests: Moved to #17.
• [x] Update tests
  • [x] Make sure existing tests pass
  • [x] tests/driver
    • [x] tests/driver/log
    • [x] tests/driver/log/test_brief.cpp
    • [x] tests/driver/log/test_child_pipe.cpp
    • [x] tests/driver/log/test_indent.cpp
    • [x] tests/driver/log/test_simple_summary.cpp
    • [x] tests/driver/log/test_summary.cpp
    • [x] tests/driver/log/test_verbose.cpp
    • [x] tests/driver/test_cmd_line.cpp
    • [x] tests/driver/test_filters.cpp
    • [x] tests/driver/test_object_factory.cpp
    • [x] tests/driver/test_run_test_files.cpp
    • [x] tests/driver/test_run_tests.cpp
    • [x] tests/driver/test_test_file.cpp
  • [x] tests/matchers
    • [x] tests/matchers/test_any_capture.cpp
    • [x] tests/matchers/test_expect.cpp
    • [x] tests/matchers/test_matchers.cpp
    • [x] tests/matchers/test_match_result.cpp
  • [x] tests/output
    • [x] tests/output/test_string_output.cpp
    • [x] tests/output/test_to_printable.cpp
    • [x] tests/output/test_type_name.cpp
  • [x] tests/suite
    • [x] tests/suite/test_attributes.cpp
    • [x] tests/suite/test_compiled_suite.cpp
    • [x] tests/suite/test_factory.cpp
    • [x] tests/suite/test_global_suite.cpp
    • [x] tests/suite/test_make_suite.cpp
    • [x] tests/suite/test_suite_execution.cpp
    • [x] tests/suite/test_test_caller.cpp
  • [x] tests/test_forward_if.cpp
  • [x] tests/test_string_algorithm.cpp
  • [x] tests/test_tuple_algorithm.cpp
  • [x] Add new tests for new code: moved to #18.
• [x] Build with bfg9000
  • [x] Basic build
  • [x] Run tests
• [x] Update documentation

[jimporter]

Expression SFINAE limitations worked around in a86d1661b15d0e327997c0c5a57dde385999a418.

[jimporter]

constexpr issues fixed in e73453296ce253ad65ecf55c95dc55a65a0fd9b7.

[jimporter]

C2797 worked around in 422662724a4cd4597b6ab4ff74b4d1acee42cd43.

[jimporter]

C3779 worked around in 6a154c041ffc6403581c2d73c03968957c5e47d7.

[jimporter]

Death tests disabled on Windows in 158e411a9e76def48a3d2f63ccde38a51457a983.

[jimporter]

libmettle and the mettle universal driver now work on Windows (though there's no Windows build system in the repo yet).

[jimporter]

Docs updated in fce75762b774c5fb3bf34c8b92cf14fd5fd9b63e.

[jimporter]

C3779 workaround removed in 0f58670926b6876b8ec1b6d36030288ca0658456. C2797 workaround removed in 49ba24a64ed305505f4e8f53bb9aaae60c03e847.

[jimporter]

This is essentially done. I don't know if we can get much better for Windows until MSVC is better (followup bugs aside).