Added generated audio for ArnoldC scripts using FreeTTS.

Hello!

To me ArnoldC is not only a programming language, it is a work of art. As such it cannot be simply executed, it should be possible to also declaim it. For this purpose, this PR adds a -declaim argument to the executable that when given quality code will produce a wave file with its output re-generated via FreeTTS.

I also updated the SBT file to use Scala 2.11.

This is the tip of the iceberg, from here it should be possible to:

* Improve the pauses so the code is more understandable
 (for example, borrowing some ideas from http://homepages.abdn.ac.uk/c.mellish/pages/papers/inlg04.pdf )
* Try to build a FreeTTS voice based on Arnie's samples
  (see http://freetts.sourceforge.net/docs/index.php#How_do_I_create_a_new_voice_How_do_I)
* Merge voice samples from https://github.com/cesardeazevedo/ArnoldC-Speaker (copyright might be an issue there, though)