Add bash script for updating copyright headers (rebased onto dev_5_0) (rebased onto develop)


This is the same as gh-1466 but rebased onto develop.

----


This is the same as gh-1462 but rebased onto dev_5_0.

----

This script is largely inspired from a Pull request from Curtis Rueden and should be called with a positional argument equal to the current year, e.g.

```
$ bash tools/update_copyright 2015
```