Use proper boost includes for different boost versions

starting from boost 1.38, there is boost.spirit v2 in the repository, older version
could be used as 'classic'

.bzrignore

@@ -36,3 +36,15 @@ vs9/mangle.sln
 *.lnk
 spec
 gmon.out
+examples/DOM/dom2pyx
+examples/DOM/domwriter
+examples/SAX/pyx
+examples/SAX/simple_handler
+examples/SAX/writer
+examples/SAX/xmlbase
+examples/Taggle/taggle
+examples/Utils/transcode
+examples/XPath/xgrep
+examples/XSLT/mangle
+m4/lt~obsolete.m4@
+

include/XPath/impl/xpath_ast.hpp

@@ -1,8 +1,17 @@
 #ifndef ARABICA_XPATHIC_XPATH_AST_HPP
 #define ARABICA_XPATHIC_XPATH_AST_HPP
 
+
+#include <boost/version.hpp>
+
+#if BOOST_VERSION >= 103800
+#define BOOST_SPIRIT_USE_OLD_NAMESPACE 1
+#include <boost/spirit/include/classic_core.hpp>
+#include <boost/spirit/include/classic_ast.hpp>
+#else
 #include <boost/spirit/core.hpp>
 #include <boost/spirit/tree/ast.hpp>
+#endif
 
 #include "xpath_ast_ids.hpp"
 

include/XPath/impl/xpath_grammar.hpp

@@ -5,9 +5,18 @@
 #define BOOST_SPIRIT_THREADSAFE
 #endif
 
+#include <boost/version.hpp>
+
+#if BOOST_VERSION >= 103800
+#define BOOST_SPIRIT_USE_OLD_NAMESPACE 1
+#include <boost/spirit/include/classic_core.hpp>
+#include <boost/spirit/include/classic_chset.hpp>
+#include <boost/spirit/include/classic_symbols.hpp>
+#else
 #include <boost/spirit/core.hpp>
 #include <boost/spirit/symbols/symbols.hpp>
 #include <boost/spirit/utility/chset.hpp>
+#endif
 
 #include "xpath_ast_ids.hpp"
 

include/XPath/impl/xpath_parser.hpp

@@ -1,8 +1,17 @@
 #ifndef ARABICA_XPATHIC_XPATH_PARSER_HPP
 #define ARABICA_XPATHIC_XPATH_PARSER_HPP
 
+#include <boost/version.hpp>
+
+#if BOOST_VERSION >= 103800
+#define BOOST_SPIRIT_USE_OLD_NAMESPACE 1
+#include <boost/spirit/include/classic_core.hpp>
+#include <boost/spirit/include/classic_ast.hpp>
+#else
 #include <boost/spirit/core.hpp>
 #include <boost/spirit/tree/ast.hpp>
+#endif
+
 #include <string>
 #include <stdexcept>
 #include <algorithm>