Run script for Linux

There's already a script for Mac OS X and Windows, so I thought a Linux one will be nice too. The main difference is using "python2" instead of "python" in case python is linked to python3 and not python2. The first commit was made by an accident. I was testing something and copied a huge python source tree, then forgot to remove it before committing. You can also just close this PR and copy the mcedit.sh script.