Moved matcher-based capture macros into their own file

- this file excluded from the CATCH_CONFIG_DISABLE_MATCHERS path.
- matchers are always compiled in to the impl file
- _THROWS_WITH macros are still available with matchers disabled - but only the ones that take a string
- tests that use matchers have #ifdefs, so the whole SelfTest project can compile with matchers disable.

include/internal/catch_capture_matchers.cpp

@@ -0,0 +1,23 @@
+/*
+ *  Created by Phil on 9/8/2017.
+ *  Copyright 2017 Two Blue Cubes Ltd. All rights reserved.
+ *
+ *  Distributed under the Boost Software License, Version 1.0. (See accompanying
+ *  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ */
+#include "catch_capture_matchers.h"
+#include "catch_interfaces_registry_hub.h"
+
+namespace Catch {
+
+    using StringMatcher = Matchers::Impl::MatcherBase<std::string>;
+
+    // This is the general overload that takes a any string matcher
+    // There is another overload, in catch_assertinhandler.h/.cpp, that only takes a string and infers
+    // the Equals matcher (so the header does not mention matchers)
+    void handleExceptionMatchExpr( AssertionHandler& handler, StringMatcher const& matcher, StringRef matcherString  ) {
+        MatchExpr<std::string, StringMatcher const&> expr( Catch::translateActiveException(), matcher, matcherString );
+        handler.handle( expr );
+    }
+
+} // namespace Catch