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, 5 insertions, 4 deletions

diff --git a/docs/tutorial.md b/docs/tutorial.md
index fb316c10..cf895705 100644
--- a/docs/tutorial.md
+++ b/docs/tutorial.md
@@ -1,6 +1,6 @@
 <a id="top"></a>
 
-> **Catch3 compatibility reference:** This page describes the bundled Catch2-compatible API. Names such as `Catch2`, `catch2/`, and `Catch2::Catch2WithMain` remain where they are actual compatibility interfaces. See [Catch3 additions](progmasoft-catch3.md) for Progmasoft APIs.
+> **Catch3 compatibility reference:** This page describes the test-writing API Catch3 shares with Catch2: the macros, such as `TEST_CASE` and `REQUIRE`, and the `Catch::` namespace keep Catch2's names. Headers and build names are Catch3's own (`<Progmasoft/Catch3/TestMacros.hpp>`, `find_package(Catch3)`, `Catch3::Catch3WithMain`). See [Catch3 additions](progmasoft-catch3.md) for Progmasoft APIs.
 
 # Tutorial
 
@@ -17,8 +17,9 @@
 
 Clone or consume [Progmasoft/catch3](https://github.com/Progmasoft/catch3),
 then use its [CMake integration](cmake-integration.md#top) or another supported
-build system. The examples in this tutorial exercise the bundled
-Catch2-compatible API, so their actual include paths remain `catch2/...`.
+build system. The examples in this tutorial use the Catch2-compatible API:
+its macros and the `Catch::` namespace, from headers such as
+`<Progmasoft/Catch3/TestMacros.hpp>`.
 For property tests, snapshots, and the result/XML writer, continue with the
 [Progmasoft extensions](progmasoft-catch3.md).
 
@@ -34,7 +35,7 @@ unsigned int Factorial( unsigned int number ) {
 ```
 
 ```c++
-#include <catch2/catch_test_macros.hpp>
+#include <Progmasoft/Catch3/TestMacros.hpp>
 
 unsigned int Factorial( unsigned int number ) {
     return number <= 1 ? number : Factorial(number-1)*number;