SED for OSX does not use -r flag

[silicontrip]

to use extended regex on OSX's sed requires the -E flag.

[silicontrip]

the following patch fixes this and #21

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4b6df3f..c964a58 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,16 +27,30 @@ if (NOT BUILD_TYPE)
     set(CMAKE_BUILD_TYPE Debug)
 endif(NOT BUILD_TYPE)
 
+if (APPLE)
+  set(CMAKE_MACOSX_RPATH 1)
+  set(SED_COMMAND sed -E)
+else(APPLE)
+  set(SED_COMMAND sed -r)
+endif()
+
 # this figures out the Python include directories and adds them to the
 # header file search path
 execute_process(
     COMMAND python-config --includes
-    COMMAND sed -r "s/-I//g; s/ +/;/g"
+    COMMAND ${SED_COMMAND} "s/-I//g; s/ +/;/g"
     COMMAND tr -d '\n'
     OUTPUT_VARIABLE Python_Includes
 )
 message(STATUS "Python include dir:" ${Python_Includes})
 
+execute_process(
+       COMMAND python-config --libs
+       COMMAND tr -d '\n'
+       OUTPUT_VARIABLE Python_Link_Flags
+)
+message(STATUS "Python link flags:" ${Python_Link_Flags})
+
 include_directories(${Python_Includes})
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 
@@ -166,6 +180,7 @@ else (USE_CLIPPER_FOR_PYTHON)
 endif (USE_CLIPPER_FOR_PYTHON)
 target_link_libraries(area ${Boost_LIBRARIES})
 set_target_properties(area PROPERTIES PREFIX "") 
+set_target_properties(area PROPERTIES LINK_FLAGS "${Python_Link_Flags}")
 
 # this figures out where to install the Python modules
 execute_process(