Changed signature of assert and retract.

The ?world instance is the first parameter of assert and retract now.
The new signature is:

 (ASSERT ?WORLD ?FACT)

and

 (RETRACT ?WORLD ?FACT)

The old predicate signatures are still valid but deprecated now.
Refactored assert for object poses.
Added occasion LOOKING-AT.
Refactored STABLE predicate.

Instead of WITH-COPIED-WORLD use COPIED-WORLD predicate and
OBJECT-POSE-DIFFERENT to compare the object poses in the two worlds.
The predicate CAMERA-FRAME has two variables now, the robot and the frame.
OCCLUDING-OBJECTS works for robot objects and poses now.
Removed executive integration subdirectory and dependency on perception_process_module.
Bugfix in physics-based designator evaluation.

If we didn't execute any checks, return :UNKNOWN, if the prolog call
failed, return :REJECT and if everything succeeds, return :ACCEPT.
Bug-fix in blocking predicate.

The %object calls must be inside the WITH-COPIED-WORLD form. Otherwise,
the objects of the original world are modified.
Suppress tf callbacks and execute them only once in projection.
Fixed reachable predicate.

It generates solutions for all possible arms. For cups, two solutions
will be generated if possible, one for left, one for right. For a pot,
only one solution will be generated. The ?ARMS variable is now a list
containing all required arms.
Refactored the BLOCKING predicate to generate choice points.

Instead of returning the list of blocking objects, the predicate now
generates one solution for each blocking object.
Merge branch 'master' into spatial-relations
Added author in manifest file.
Got rid of a bunch of format statements.
Added a todo.
Fixed symbolic link to asd file.
Deleted file 'unused-code.lisp'.
changed `pose parked' into `to park'
Merge branch 'master' of https://github.com/moesenle/cram_physics