Drop required Boost version from 1.37 to 1.34

Use boost/tr1 to bring in std::tr1::unordered_map instead of the Boost
version.

acinclude.m4

@@ -671,7 +671,7 @@ if test "x$want_boost" = "xyes"; then
 		if test "$_version" = "0" ; then
 			AC_MSG_ERROR([[We could not detect the boost libraries (version $boost_lib_version_req_shorten or higher). If you have a staged boost library (still not installed) please specify \$BOOST_ROOT in your environment and do not give a PATH to --with-boost option.  If you are sure you have boost installed, then check your version number looking in <boost/version.hpp>. See http://randspringer.de/boost for more documentation.]])
 		else
-			AC_MSG_NOTICE([Your boost libraries seems to old (version $_version).])
+			AC_MSG_ERROR([Your boost libraries seems to old (version $_version).])
 		fi
 	else
 		AC_SUBST(BOOST_CPPFLAGS)

configure.ac

@@ -37,7 +37,7 @@ AC_PROG_CXX
 AC_PROG_RANLIB
 AC_PROG_INSTALL
 AC_PROG_LN_S
-AX_BOOST_BASE([1.37.0])
+AX_BOOST_BASE([1.34.0])
 
 if test "x$BOOST_CPPFLAGS" != "x-I/usr/include" ; then
    CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"

simgear/scene/material/Effect.hxx

@@ -19,8 +19,9 @@
 
 #include <vector>
 #include <string>
+#include <boost/tr1/unordered_map.hpp>
 
-#include <boost/unordered_map.hpp>
+#include <boost/functional/hash.hpp>
 
 #include <osg/Object>
 #include <osgDB/ReaderWriter>
@@ -132,8 +133,8 @@ protected:
             bool operator()(const Key& lhs, const Key& rhs) const;
         };
     };
-    typedef boost::unordered_map<Key, osg::ref_ptr<Effect>, boost::hash<Key>,
-                                 Key::EqualTo> Cache;
+    typedef std::tr1::unordered_map<Key, osg::ref_ptr<Effect>,
+                                    boost::hash<Key>, Key::EqualTo> Cache;
     Cache* getCache()
     {
         if (!_cache)