Added a README file, also look at matlab.h comments!

wrap/README

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+Frank Dellaert
+October 2011
+
+The wrap library wraps the GTSAM library into a MATLAB toolbox.
+
+It was designed to be more general than just wrapping GTSAM, but a small amount of 
+GTSAM specific code exists in matlab.h, the include file that is included by the
+mex files. In addition, the current makefile (Oct 11) is GTSAM specific.
+
+The classes and methods to be warpped are specified in gtsam.h
+This tool will not wrap arbitrary methods. Please read comments in matlab.h
+Some good things to know:
+
+OBJECT CREATION
+- Classes are created by special constructors, e.g., new_GaussianFactorGraph_.cpp.
+	These constructors are called from the MATLAB class @GaussianFactorGraph.
+	new_GaussianFactorGraph_ calls wrap_constructed in matlab.h, see documentation there
+	
+METHOD (AND CONSTRUCTOR) ARGUMENTS
+- simple argument types of methods, such as "double", will be converted in the
+  mex warppers by calling unwrap<double>, defined in matlab.h
+- Vector and Matric arguments are normally passed by reference in GTSAM, but
+  in gtsam.h you need to pretedn they are passed by value, to trigger the 
+  generation of the correct conversion routines unwrap<Vector> and unwrap<Matrix>
+- passing classes as arguments works, provided they are passed by reference.
+	This triggers a call to unwrap_shared_ptr
+