Give Catch3 its own build names and headers

Catch2 compatibility means the API tests are written in: the macros, such
as TEST_CASE and REQUIRE, and the Catch:: namespace. It does not mean
Catch2's build names or header paths. find_package(Catch2) found Catch3,
and a project using both frameworks met two packages, two sets of targets,
two Catch.cmake modules and two catch2/ header trees with the same names.

Build names:
- CMake: project and package Catch3, targets Catch3::Catch3 and
  Catch3::Catch3WithMain, libraries Catch3 and Catch3Main, options
  CATCH3_*, lib/cmake/Catch3 with Catch3Config, and pkg-config catch3 and
  catch3-with-main. The version is Catch3's, 0.3.0, compatible within a
  minor version.
- The CMake scripts are Catch3.cmake (catch3_discover_tests),
  Catch3AddTests.cmake and Catch3ShardTests.cmake
  (catch3_add_sharded_tests); the helpers they define at ctest time have a
  catch3_ prefix. ParseAndAddCatchTests.cmake, deprecated upstream, is gone.
- Bazel //:catch3 and //:catch3_main, Meson catch3 and catch3-with-main
  (with override_dependency), Xmake catch3 and catch3_main, Premake Catch3
  and Catch3WithMain. Visual Studio projects get GUIDs of their own.
- The Progmasoft::Catch3 target and package are gone: property testing
  and snapshots are part of Catch3::Catch3. Their sources now build with
  the library's warning flags, so property failures are built field by
  field (no missing initializers) and the default property name is a
  thread-local pointer to the name its scope owns (no global destructor).

Headers: the engine moved from src/catch2 to src/Progmasoft/Catch3 with
Progmasoft names, so <catch2/catch_test_macros.hpp> is
<Progmasoft/Catch3/TestMacros.hpp>, <catch2/matchers/catch_matchers_string.hpp>
is <Progmasoft/Catch3/Matchers/String.hpp>, and interface headers are named
after their interface, such as Interfaces/IConfig.hpp. Include guards
became #pragma once. The installed headers go to include/Progmasoft.
src/Progmasoft/Context.cpp is StrategyContext.cpp, so no two sources share
a file name.

tools/scripts/upstreamFiles.txt lists the files that come from Catch2.
The license check expects BSL-1.0 on them and Progmasoft's header on the
rest of src/Progmasoft; the convenience-header check, the amalgamation
script and the surrogate tests take the engine's headers from it. The
amalgamated files are regenerated. The header-guard workflow checks for
#pragma once instead of checkguard.

Documents, the README and the release notes describe the new names.

1 files changed, 61 insertions, 0 deletions

diff --git a/src/Progmasoft/Catch3/Internal/ReusableStringStream.hpp b/src/Progmasoft/Catch3/Internal/ReusableStringStream.hpp
new file mode 100644
index 00000000..852d2fa3
--- /dev/null
+++ b/src/Progmasoft/Catch3/Internal/ReusableStringStream.hpp
@@ -0,0 +1,61 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+#pragma once
+
+#include <Progmasoft/Catch3/Internal/NonCopyable.hpp>
+
+#include <iosfwd>
+#include <cstddef>
+#include <ostream>
+#include <string>
+
+namespace Catch {
+
+    class ReusableStringStream : Detail::NonCopyable {
+        std::size_t m_index;
+        std::ostream* m_oss;
+    public:
+        ReusableStringStream();
+        ~ReusableStringStream();
+
+        //! Returns the serialized state
+        std::string str() const;
+        //! Sets internal state to `str`
+        void str(std::string const& str);
+
+#if defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+// Old versions of GCC do not understand -Wnonnull-compare
+#pragma GCC diagnostic ignored "-Wpragmas"
+// Streaming a function pointer triggers Waddress and Wnonnull-compare
+// on GCC, because it implicitly converts it to bool and then decides
+// that the check it uses (a? true : false) is tautological and cannot
+// be null...
+#pragma GCC diagnostic ignored "-Waddress"
+#pragma GCC diagnostic ignored "-Wnonnull-compare"
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpointer-bool-conversion"
+#pragma clang diagnostic ignored "-Wmicrosoft-cast"
+#endif
+
+        template<typename T>
+        auto operator << ( T const& value ) -> ReusableStringStream& {
+            *m_oss << value;
+            return *this;
+        }
+
+#if defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+        auto get() -> std::ostream& { return *m_oss; }
+    };
+}
+