Changed grasp type decision from object-type `handled' to occurence of handles

The grasping type being executed (as called by `to grasp') is now chosen based on
occurrences of handles on an object designator instead of the object-type `handled'.
This makes space for the object-types that are actually used (pot, mug, ...) and
removed redundancy in terms of handle presence.
Merge branch 'master' of https://github.com/moesenle/cram_pr2
Removed the `handles' and `handled' properties

Whether an object designator has handles or not is now solely based on the
presence of `handle' properties on the respective object designator.
Introduced put-down functions for handled objects

Prepared functions for putting down objects that have handles.
The functions are mostly dummies atm and are in active development.
Extended the handle description by an object designator for handle radius.

The handles on an object are now described by an object designator.
This designator consists of a location designator for the relative handle pose and a radius attribute for the handle itself.
All functions have been refactored to use this new type of description. Grippers are opened and closed appropriately now.
Added a function to reflect changes in grasping on specific handles

The function `update-handle-grasp-status' takes a handle designator and a gripper side as arguments and creates a new designator reflecting changes in grasping. Also, a property "grasped-by" is introduced to specify this property on designators.
Slightly optimized code by reusing functions

Replaced a few lines of code to reuse functions already defined in cram-designators.
Completed grasp status updating for handle designators

The function `update-handle-grasp-status' now properly defines the gripper in which a handle currently resides. The handle designator as well as the corresponding object designator of the handled object are updated and equated to their previous versions. Also, removed lift-handle-object-with-relative-location from grasp-object-with-handles since it is not part of the grasping. Updates documentation strings accordingly.
Removed the function for updating handle designators for now

Removed the function `update-handle-pregrasp-status' for now since it would be unused. Therefore, designators of object handles are not updated concerning the gripper they are grasped with.
Also removed some unnecessary functions (putdown-with-handles) due to availability of that functionality from other modules (cram_environment_representation).
Also, the radius for handles is now properly implemented in the process module.
Added pass-through of return values to pm-execute for manipulation-tasks

The return value of action-handlers during manipulation-tasks was not passed through to the calling instance. This is fixed now.
Moved functions for handling objects with handled to handled-objects.lisp

Removed the functions specified for handled objects from the main `process-module.lisp' and placed them in a dedicated file `handled-objects.lisp'. Also, set up the appropriate dependencies in the .asd file.
Updated .gitignore file

Added *#* instead of *# files so that ./.#foo files are not taken into account when committing.
Moved parameters from main file to motion library

Several defparameter's were moved from the main `process-module.lisp' file into the motion library file `motion-library.lisp'.
Moved functions that actually move the arms into motion-library.lisp

All functions that execute arm trajectories were moved into `motion-library.lisp' and removed from `process-module.lisp' for clarity.
Added missing `radius' property

The missing designator property `radius' was added to the pr2-manipulation-process-module package.lisp.
Fixed indentation

Fixed the indentation in package.lisp
Moved def-action-handler macro into motion-library

Since the macro is important for all action handlers, it is moved into the same file `motion-library.lisp'.
Changed the pointing frame for head movements to `high_def_frame'

Since `head_pan_link' seems to not work anymore, the pointing frame is changed to the more recent `high_def_frame'.
Added functions for creating handled object designators

Convenience functions for creating designator objects of handled objects have been introduced. `make-handled-object-designator' takes two key arguments:
 - :handles takes a list of object-relative handle poses and their respective radius as an argument
 - :object-type takes the type of the new object designator as an argument
A sample call to this function would be
(pr2-manip-pm::make-handled-object-designator :object-type :pot :handles `((pose-1 0.01) (pose-2 0.02)))
resulting in an object of type ":pot" that has two handles (at relative poses pose-1 and pose-2 with radius 0.01 and 0.02, respectively).
Removed unnecessary newlines

Several files had unnecessary additional newlines between functions.
Removed them.