Handle long categorisation names.

[pwhipp]

The long labels are always going to be a bit of a pain. A couple of options:

1. Bite the bullet and use wider m2m fields (this is a few hours work because of all the dependent hard coded widths)
2. Introduce an abbreviation in association with the themes/sub themes and auto generate/allow editing of it. Then use it by default in the selection/filtering.

For autogeneration I could take the first letter of each word and then disambiguate any collisions with an integer.

The abbreviation route is probably better in the long term because we allow very long names which may require revisiting of any revised width setting.

[cccs-ip]

Can you please give an example of how the abbreviations would look? Isn't this more or less the same thing I was suggesting under Issue #124 ?

[pwhipp]

My bad. I didn't notice #126 when I entered this.