Bigger tests

gpaw/test/big/, doc/tutorials/

In these folders there are * scripts (advanced gpaw test system) that define workflows that we run when I remember to run them every weekend on the Niflheim supercomputer using MyQueue:

$ mq workflow -p .
Scanning 99 scripts:  |--------------------| 100.0%
Submitting 350 tasks: |--------------------| 100.0%


from myqueue.workflow import run

def workflow():
    """Run jellium tutorial and create fig2.png."""
    run(script='', cores=4)
    with run(script='', cores=4, tmax='1h'):
        with run(script=''):