Update README, showing how to wrap other projects using gtsam

cython/README.md

@@ -51,6 +51,49 @@ Examples:
       noiseGaussian = dynamic_cast_noiseModel_Gaussian_noiseModel_Base(noiseBase)       
 ```
 
+WRAPPING YOUR OWN PROJECT THAT USES GTSAM
+=========================================
+
+- Set PYTHONPATH to include ${GTSAM_CYTHON_TOOLBOX_PATH}
+  + so that it can find gtsam Cython header: gtsam/gtsam.pxd
+
+- Create your setup.py.in as follows:
+```python
+from distutils.core import setup
+from distutils.extension import Extension
+from Cython.Build import cythonize
+import eigency
+
+include_dirs = ["${CMAKE_SOURCE_DIR}/cpp", "${CMAKE_BINARY_DIR}"]
+include_dirs += "${GTSAM_INCLUDE_DIR}".split(";")
+include_dirs += eigency.get_includes(include_eigen=False)
+
+setup(
+    ext_modules=cythonize(Extension(
+        "your_module_name",
+        sources=["your_module_name.pyx"],
+        include_dirs= include_dirs,
+        libraries=['gtsam'],
+        library_dirs=["${GTSAM_DIR}/../../"],
+        language="c++",
+        extra_compile_args=["-std=c++11"])),
+)
+
+```
+
+- In your CMakeList.txt
+```cmake
+find_package(GTSAM REQUIRED) # Make sure gtsam's install folder is in your PATH
+set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH}" "${GTSAM_DIR}/../GTSAMCMakeTools")
+# Wrap
+include(GtsamCythonWrap)
+wrap_and_install_library_cython("your_project_interface.h"
+                                "from gtsam.gtsam cimport *" # extra import of gtsam/gtsam.pxd Cython header
+                                "path_to_your_setup.py.in"
+                                "your_install_path"
+```
+
+
 
 KNOWN ISSUES
 ============