Updated compile instructions to new msys.

README.md

@@ -12,21 +12,19 @@ Install the dependencies.
 ### Unix
 ```bash
 $ autoconf
-# OPENMODELICAHOME is usually /usr, /opt, /opt/openmodelica, or /path/to/svn/OpenModelica/build
+# OPENMODELICAHOME is usually /usr, /opt, /opt/openmodelica, or /path/to/OpenModelica/build
 $ ./configure --prefix=/path/to/OPENMODELICAHOME CXX=clang++
 $ make
 $ make install
 ```
 
 ### Windows MinGW
-- Download the Qt SDK for windows from http://qt.nokia.com/downloads.
-- Qt 4.8.0 comes with MSVC tool chain by-default. Make sure you install the MINGW tool chain also. Use the MINGW tool chain while compiling.
-- If you don't have OMDev then download it from the svn repository here https://openmodelica.org/svn/OpenModelicaExternal/trunk/tools/windows/OMDev.
-- Download OMDev in c:\OMDev. Set the environment variable OMDEV which points to c:\OMDev.
-- Run the OMShell/OMShellGUI/Makefile.omdev.mingw via Qt Command Prompt.
+- If you don't have OMDev then download it from the svn repository [here](https://openmodelica.org/svn/OpenModelicaExternal/trunk/tools/windows/OMDev).
+- Follow the instructions in [INSTALL.txt](https://openmodelica.org/svn/OpenModelicaExternal/trunk/tools/windows/OMDev/INSTALL.txt).
+- Open msys terminal. Either `$OMDEV/tools/msys/mingw32_shell.bat` OR `$OMDEV/tools/msys/mingw64_shell.bat`.
 ```bash
-$ cd OMShell/OMShellGUI
-$ make -f Makefile.omdev.mingw OMBUILDDIR=/path/to/OpenModelica/build
+$ cd /path/to/OpenModelica
+$ make -f Makefile.omdev.mingw omshell
 ```
 - Start OMShell from /path/to/OpenModelica/build/bin/OMShell.exe