Show current git branch in node editor header

Created by: ly29

This would be so extremely useful for development...

For me the following works well, in the blender console.

import subprocess
import os
import sverchok
res = subprocess.run(["git", "rev-parse", "--abbrev-ref", "HEAD"],
                            stdout=subprocess.PIPE, 
                            cwd=os.path.dirname(sverchok.__file__))
branch = str(res.stdout.decode("utf-8"))
print(branch)

If it works for you I will implement it.