Multi character

This branch adds MultiCharacter which shows two or more dialogues in a window.

Here is an example script and a screen shot.
https://gist.github.com/vbkaisetsu/136088bc34e26b3d12ec

Movie:
http://youtu.be/4TByQj4tHdc

![multicharacter](https://f.cloud.github.com/assets/2175479/289016/89504d90-9290-11e2-9efa-3f40c4cf31ca.png)