Add support for MacOsX

bin/README.txt

@@ -4,7 +4,8 @@ The same way you can use 'java.library.path' option as well.
 By default binding expects 'imgui-java' ('imgui-java64' for x64 arch) file name.
 You can change that by using 'imgui.library.name' VM option (ex: -Dimgui.library.name=custom-lib-name).
 
-- imgui-java.dll     << win32
-- imgui-java64.dll   << win64
-- libimgui-java.so   << linux32
-- libimgui-java64.so << linux64
+- imgui-java.dll        << win32
+- imgui-java64.dll      << win64
+- libimgui-java.so      << linux32
+- libimgui-java64.so    << linux64
+- libimgui-java64.dylib << MacOs64