Add testing of standalone mode.

Allow tests to be built in standalone mode.
Update CI.
Update docs.

test/regress/basic_tests.cpp

@@ -16,14 +16,6 @@
   *   DESCRIPTION: main regex test declarations.
   */
 
-#include <boost/detail/workaround.hpp>
-
-#if BOOST_WORKAROUND(BOOST_BORLANDC, < 0x560)
-// we get unresolved externals from basic_string
-// unless we do this, a well known Borland bug:
-#define _RWSTD_COMPILE_INSTANTIATE
-#endif
-
 #include "test.hpp"
 
 #ifdef BOOST_MSVC

test/regress/main.cpp

@@ -217,6 +217,13 @@ int main(int argc, char * argv[])
    return cpp_main(argc, argv);
 }
 
+#elif defined(BOOST_REGEX_STANDALONE)
+
+int main(int argc, char* argv[])
+{
+   return cpp_main(argc, argv);
+}
+
 #else
 
 #include <boost/detail/lightweight_main.hpp>

test/regress/test.hpp

@@ -27,6 +27,23 @@
 #pragma warning(disable:1418 981 383 1419 7)
 #endif
 
+#ifndef BOOST_WORKAROUND
+#define BOOST_WORKAROUND(x, y) false
+#endif
+#ifdef BOOST_REGEX_STANDALONE
+#include <cstdint>
+
+namespace boost { using std::uint32_t; }
+
+#define BOOST_JOIN(X, Y) BOOST_DO_JOIN(X, Y)
+#define BOOST_DO_JOIN(X, Y) BOOST_DO_JOIN2(X,Y)
+#define BOOST_DO_JOIN2(X, Y) X##Y
+
+#define BOOST_STRINGIZE(X) BOOST_DO_STRINGIZE(X)
+#define BOOST_DO_STRINGIZE(X) #X
+
+#endif
+
 #include <typeinfo>
 #include "test_not_regex.hpp"
 #include "test_regex_search.hpp"

test/regress/test_icu.cpp

@@ -20,10 +20,25 @@
 // We can only build this if we have ICU support:
 //
 #include <boost/regex/config.hpp>
+
+#ifdef __has_include
+#if __has_include(<unicode/utypes.h>)
+#define BOOST_HAS_ICU
+#endif
+#endif
+
 #if defined(BOOST_HAS_ICU) && !defined(BOOST_NO_STD_WSTRING)
 
 #include <boost/regex/icu.hpp>
+#ifndef BOOST_REGEX_STANDALONE
 #include <boost/mpl/int.hpp>
+#else
+#include <type_traits>
+namespace boost { namespace mpl {
+   template <int I>
+   using int_ = ::std::integral_constant<int, I>; 
+} }
+#endif
 #include "test.hpp"
 
 namespace unnecessary_fix{

test/regress/test_mfc.cpp

@@ -19,7 +19,7 @@
 //
 // We can only build this if we have ATL support:
 //
-#include <boost/config.hpp>
+#include <boost/regex/config.hpp>
 
 #ifdef TEST_MFC