Update CMakeLists.txt

Compile on MacOS 
fix JakobEngel#26

Also I have problem with code compile. Fixed by changing type of `connectivityMap` to:

    std::map<uint64_t,Eigen::Vector2i> connectivityMap;

CMakeLists.txt

@@ -115,11 +115,17 @@ add_library(dso ${dso_SOURCE_FILES} ${dso_opencv_SOURCE_FILES} ${dso_pangolin_SO
 #set_property( TARGET dso APPEND_STRING PROPERTY COMPILE_FLAGS -Wall )
 
 
+if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin") # OSX
+    set(BOOST_THREAD_LIBRARY boost_thread-mt)
+else()
+    set(BOOST_THREAD_LIBRARY boost_thread)
+endif()
+
 # build main executable (only if we have both OpenCV and Pangolin)
 if (OpenCV_FOUND AND Pangolin_FOUND)
 	message("--- compiling dso_dataset.")
 	add_executable(dso_dataset ${PROJECT_SOURCE_DIR}/src/main_dso_pangolin.cpp )
-    target_link_libraries(dso_dataset dso boost_system boost_thread cxsparse ${LIBZIP_LIBRARY} ${Pangolin_LIBRARIES} ${OpenCV_LIBS})
+    target_link_libraries(dso_dataset dso boost_system cxsparse ${BOOST_THREAD_LIBRARY} ${LIBZIP_LIBRARY} ${Pangolin_LIBRARIES} ${OpenCV_LIBS})
 else()
 	message("--- not building dso_dataset, since either don't have openCV or Pangolin.")
 endif()