Revert "Use preprocessor directives to support Swift 2.x"
Revert "Use preprocessor directives to support Swift 2.x"

This reverts commit 1693f11c2ea1729d46b4a85bd5e40e6c1211a8a3.

There's no point as the interface to Date/NSDate has also changed.

Reverting.

UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples,UCL-RITS/pi_examples