[ros] change XmlRpc namespace to avoid conflict

YARP and ROS both use the XmlRpc++ library.  When YARP is
compiled statically, these libraries can conflict if the
user is also linking ROS.  (This is not a problem when
YARP is compiled as a shared library, where the
XmlRpc-related symbols are not exposed).  To support
static linking, the XmlRpc namespace in YARP is renamed
to YarpXmlRpc.  See #167
 New interface IInteractionMode: this interface will be used to set the robot
   in STIFF or COMPLIANT mode as a different way of interaction with the world.

 First implementation -- seems to work.
ControlBoardWrapper: Fix, un-paired '{' removed
yarp::dev: AddeIControlInterface2 which introduces the generic setControlMode method.
add new controlMode Mixed: accepts both position and velocity commands at the same time.
                    Force_idle: same as idle, but reset hardware faults, if any.

add vocabs for signalling special status from the board, if needed. Those are
                    Hardware Fault
                    Calibrating / Calib done
                    Not configured yet / Initial config done
IPositionDirect: add setPositionDirect method in IPositionDirect interface and
  relative implementation in the remoteControlBoard and in the controlBoardWrapper
Fix typo in IVelocityControlInterface
ControlBoardWrapper: add missing getControlModes group
Implement ControlInterface2: added implementation and declaration of IControl(1) methods
RemoteControlBoard: changed PositionDirectMode() to not use the iControl2 interface
ControlBoardWrapper: changed parsing of incoming setControlMode messages.
Fix error on PositionDirect(), added Torque()
ControlBoardWrapper: revert setPositionMode() to use iControlMode1->setPositionMode(j)
ControlBoardWrapper: fix add missinf break in a switch case