pr2 manipulation knowledge now holds explicit information about PR2 kinematics

The module now offers ''crs:prolog'' facts that inform about the palm link, the default (identity) orientation, and the planning group for a given arm side ('':left'', '':right'').
Instead of hard-coding kinematic links, read them from ''crs:prolog''

Links, orientations, and planning groups are now read from ''pr2_manipulation_knowledge'' rather than hard-coding them in the ''pr2_manipulation_process_module'' code. This makes changing of global values very easy, allows for handling different arm sides differently using a central mechanism (aka ''crs:prolog'' facts) and offers less opportunities for typos, mix-ups, and confusion. Also, the code now gets a meaning rather than a bunch of meaningless string variables.