Starting to generalize the GridSlamProcessor class.

Starting to generalize the GridSlamProcessor class to manage more than one
laser. The function setSensorMap is not being used now. More work is needed
though: remove the gsp_laser_ variable, and use of specific laser paramers when
needed, ie, do not store them with setLaserParameters.
More integration with the SensorMap.

SensorMap is correctly deleted on class destruction.
Laser orientation and angle increment are independent and are
stored within the RangeSensor class (two new arguments on the
constructor).
Variables gsp_laser_ and gsp_laser_angle_increment_ have been
removed.
Array of laser angles now initiated on sensor constructor.

Now it is no longer created on each updateMap call.
Unused variables deleted.
Particles are now published on its own thread.

New flag to know if the GridSlamProcessor is initialized.