testing
galilei is all finished up, must still work on the reactions
This commit updates the following elements of ESPResSo.
1) It removes the Tcl functions: stop_particles, stopParticles, system_com, system_com_vel, and galileiTransformParticles, which were in the auxiliary.tcl script.
2) It replaces these with MPI functions: kill_particle_motion, kill_particle_forces, system_CMS, system_CMS_velocity, and galilei_transform (respectively). These new functions are incorporated in a new feature called 'GALILEI'.
3) It changes the Hat-potential entry in the user guide to be more clear on what the cut-off radius is and what the radial dependence is.
4) It updates the reaction code with two options:
   (a) Letting each reactant interact only with one catalyst particle during each time step. This enables the creation of catalytic surfaces comprised of catalyst particles (with arbitrary density), yet maintaining a surface-density-independent reaction rate near the surface.
   (b) A print option is given to the reaction command, such that the specific input parameters can be returned to the Tcl level.
5) All the necessary  updates are made in the user guide.
Merge branches 'galilei' and 'galilei_transform' into galilei_transform
Also included the files I missed earlier.
Simple angular velocity observable added, must still add more complex angular auto-correlation function.
new velocity boundary conditions for LBPU

the implementation is completely analogous to the CPU implementation
Repaired compilor error in case ROTATION feature is not compiled in.
Added external torque to the EXTERNAL_FORCES feature. Added documentation on the external torque to the user's guide as well as on the particle_angular_momentum observable. Removed some depricated commands from the .tcl files in the scripts, samples and testsuite folders, such that the command names from the GALILEI feature are now used.
Merge branch 'master' into torque
fixed the pressure tensor calculation for LB

and added a quite powerful testcase that
checks Couette and Poisseuille flow and
hydrostatic pressure in planar geometries
added pressure calculation for GPU
Merge branch 'lbgpu_development'
fixed pressure tensor for GPU LB and made testcase
Using flat noise for Gaussian + GPU LB only print_interpolated_velocity
Merge Conflicts fixed
Merge branch 'master', remote-tracking branch 'upstream'
Merge conflicts again
Made the REACTIONS code more efficient and removed minor bug from UG.
Merge failure resolved