make sure people git clone OMDev properly

Belonging to [master]:
  - #2607

Author: adrpo

README-OMDev-MINGW.md

@@ -1,14 +1,23 @@
 # Compiling OMC using OMDev package
 
-- Checkout the OMDev package from SVN https://openmodelica.org/svn/OpenModelicaExternal/trunk/tools/windows/OMDev or git clone it from https://openmodelica.org/git/OMDev.git (much faster)
+- Checkout the OMDev package
+  - Install git for windows https://git-scm.com/downloads
+  - make sure we git clone with the correct line endings, run in a terminal:
+    ```bash
+      git config --global core.eol lf
+      git config --global core.autocrlf input
+	```
+  - get OMDev from git
+     ```bash
+	  git clone https://openmodelica.org/git/OMDev.git
+	 ```
   - this package contains all prerequisites to compile OMC on Windows using msys2+mingw32+mingw64
-  - if you get issues with OpenModelica compilation maybe you should update OMDev
+  - if you get issues with OpenModelica compilation maybe you should update OMDev (git pull)
   - please make sure you have OMDEV environment variable defined and that you have restarted or logout/login to make it available
 - Make sure you place the OMDev package into `C:\OMDev\`
   - Follow the instructions in the `C:\OMDev\INSTALL.txt` file
 - Install Java SE Development Kit (for javac)
-- Install svn tools for windows in TortoiseSVN
-- Install git for windows https://git-scm.com/downloads
+- Install svn tools for windows in TortoiseSVN (needed to checkout some of the Modelica libraries)
   - do not install git using pacman in msys, it does not work correctly!
 - get OpenModelica from git
   - do not create an OpenModelica directory in which you clone OpenModelica repository, it will be created when you clone it