Remove catch.hpp

This was an old "include all" header, that we no longer want to be
usable, to make the include differences in new versions explicit.

We will introduce new "include all" headers later, in the form of
`catch_all.hpp`, `catch_matchers_all.hpp` and so on...

examples/010-TestCase.cpp

@@ -4,7 +4,7 @@
 #include <catch2/catch_default_main.hpp>
 
 // And write tests in the same file:
-#include <catch2/catch.hpp>
+#include <catch2/catch_test_macros.hpp>
 
 static int Factorial( int number ) {
    return number <= 1 ? number : Factorial( number - 1 ) * number;  // fail

examples/020-TestCase-1.cpp

@@ -6,7 +6,7 @@
 // Let Catch provide main():
 #include <catch2/catch_default_main.hpp>
 
-#include <catch2/catch.hpp>
+#include <catch2/catch_test_macros.hpp>
 
 TEST_CASE( "1: All test cases reside in other .cpp files (empty)", "[multi-file:1]" ) {
 }

examples/020-TestCase-2.cpp

@@ -2,7 +2,7 @@
 
 // main() provided by Catch in file 020-TestCase-1.cpp.
 
-#include <catch2/catch.hpp>
+#include <catch2/catch_test_macros.hpp>
 
 static int Factorial( int number ) {
    return number <= 1 ? number : Factorial( number - 1 ) * number;  // fail

examples/030-Asn-Require-Check.cpp

@@ -10,7 +10,7 @@
 
 // main() provided in 000-CatchMain.cpp
 
-#include <catch2/catch.hpp>
+#include <catch2/catch_test_macros.hpp>
 
 static std::string one() {
     return "1";

examples/120-Bdd-ScenarioGivenWhenThen.cpp

@@ -2,7 +2,7 @@
 
 // main() provided in 000-CatchMain.cpp
 
-#include <catch2/catch.hpp>
+#include <catch2/catch_test_macros.hpp>
 
 SCENARIO( "vectors can be sized and resized", "[vector]" ) {