Removed the DisplayGroupInterface and its subclasses.

Change-Id: I321b1064222ebc343e23276e1b6a5ef3f7ff236f
Removed obsolete support for Python, Skeletons and Joystick (OpenNI, SDL).

Change-Id: I8cb705d48d6542040347cf1826723b66070cdd3b
Finished removing DisplayGroupInterface

Change-Id: Ic0e71bb26637d02ad317a4e95e4b888cdf07cb23
Removing obsolete TouchListener (superseeded by MultiTouchListener).

Change-Id: I0ff03a363e691fe138b381681d776b002c324846
Merge pull request #111 from rdumusc/displaygroupinterface

Merged DisplayGroup and DisplyGroupInterface.
Removing ContentWindowInterface.

Change-Id: Ibb6a08e87f211ff9891f8d65790c0142b77a9cc3
Cleaning Content dimensions handling.

Change-Id: I2f8f9d8ada408a6c6a45f1f85e94531cdc578996
DisplayGroup classes use an MVC pattern.

Change-Id: Ic861ec9da35f66b51ec73323db99bf7d57029653
Improve the handling of ContentWindow Events.
Fix build with Poppler system packages.

Change-Id: Ia354d1040b1be76f84429df20558f056404d7121
Merge pull request #112 from rdumusc/contentwindowinterface

Merging ContentWindow with ContentWindowInterface