Fix issue #1

Use CXXFLAGS instead of CFLAGS, and update docs on difference between
MATLAB/OS X/Linux/Windows.

matlab/README.md

@@ -10,8 +10,24 @@ Usage
 The MATLAB MEX functions need to be compiled before use. To do so, run
 
 ```Shell
-mex CFLAGS='$CFLAGS -std=c++11' ddm_fpt.cpp ../src/ddm_fpt_lib.cpp
-mex CFLAGS='$CFLAGS -std=c++11' ddm_fpt_full.cpp ../src/ddm_fpt_lib.cpp
+mex CXXFLAGS='$CXXFLAGS -std=c++11' ddm_fpt.cpp ../src/ddm_fpt_lib.cpp
+mex CXXFLAGS='$CXXFLAGS -std=c++11' ddm_fpt_full.cpp ../src/ddm_fpt_lib.cpp
 ```
 
-at the command line. The location of the `mex` executable and exact syntax for specifying the compiler flags might be OS-dependent.
+at the MATLAB prompt. Alternatively, the files can be compiled at the shell. Do do so, use
+
+```Shell
+mex CXXFLAGS="$CXXFLAGS -std=c++11" ddm_fpt.cpp ../src/ddm_fpt_lib.cpp
+mex CXXFLAGS="$CXXFLAGS -std=c++11" ddm_fpt_full.cpp ../src/ddm_fpt_lib.cpp
+```
+
+at the Windows Command Prompt (using double quotes, (")), or
+
+```Shell
+mex CXXFLAGS='$CXXFLAGS -std=c++11' ddm_fpt.cpp ../src/ddm_fpt_lib.cpp
+mex CXXFLAGS='$CXXFLAGS -std=c++11' ddm_fpt_full.cpp ../src/ddm_fpt_lib.cpp
+```
+
+at the Mac and Linux shell command line (using single quotes (')). Note that, for older versions of MATLAB, all occurences of `CXXFLAGS` might need to be replaced with `CFLAGS`.
+
+The location of the `mex` executable and exact syntax for specifying the compiler flags might be depend on OS and installation details.