minor documentation fixes, dead build info link

Documentation/DeveloperHelpSources/building.docu

@@ -36,8 +36,8 @@ for your specific operating system.
 
 <ul>
 <li> First install the required libraries via your linux distributions package management e.g. apt or rpm (for the list of packages see above)<br />
-<li> Extract the source code or get it via svn:<br />
-<code><b> svn co http://www.openflipper.org/svnrepo/OpenFlipper/branches/Free OpenFlipper</b></code></li>
+<li> Extract the source code or get it via git:<br />
+<code><b> git clone --recursive https://graphics.rwth-aachen.de:9000/OpenFlipper-Free/OpenFlipper-Free.git OpenFlipper</b></code></li>
 <li> Create a build directory (e.g. <b>build</b>) in the toplevel directory: <code><b>mkdir build</b></code></li>
 <li> Change to the newly created directory <code><b>cd build</b></code> and type <code><b>cmake ..</b></code></li>
 <li> Now call  <b>make</b> to build OpenFlipper </li>