Minor glitches

Hi Andrew,

Here are just a couple of very minor bugs I have come across that I thought I would get you to merge with master before they get caught up in something else. 

Please ignore all the merge related commits (I should have squashed them before pushing to github), the only changes are the passing-on of the 'clear' kwarg in write_data and removing 'StandardCellType' from the list of standardmodels for neuron.

Cheers,

Tom