Add context global to the mocha BDD interface

For mocha compatibility
Allow accessing the timeout in hooks

For Mocha compatibility
Allow setting timeout with this.currentTest.timeout(x)

For Mocha compatibility
Add support for displaying tests that time out to spec progress reporter

No test because this file is not tested yet :-/
Count tests that time out in the summary reporter
Rename begin messages to start messages

To match the wording: start/finish
Remove unused function argument

Copy/paste error
Add utilities for pretty printing error messages
Add some more error message utilities

This will be used by the error detail reporter
Make tests work in overman too