Make rotation switchable on a per-particle level

When SWITCHABLE_ROTATION is defined in myconfig.h,
part ... rotation 1
activates rotation for a specific particle.
SWITCHABLE_ROTATION is incompatible with pressure calculation, as there is no method to count the number of degrees of freedom, yet.
SWITCHABLE_ROTATION: Added to feature list in config.c
Dipolar all with all - no replicas: Respect boundary conditions set by setmd
SWITCHABLE_ROTATION implies ROTATION.

Conflicts:

	communication.c
	config.h
Merge branch 'master' into switchable-rotation.

Conflicts:
	doc/ug/features.tex
	doc/ug/part.tex
	myconfig-sample.h
	src/communication.c
	src/config.c
	src/config.h
	src/magnetic_non_p3m_methods.c
	src/pressure.c
	src/pressure.h
in add_constraint_force, exit early if no constraints are active
The code from check_forces() which checks if a force is nan
into rescale_forces...() to avoid an additional iteration over all particles
Bugfix to thermostat: Fixed particles got thermostat forces
Merge branch 'master' into switchable_rotation2
Fixed ROTATION_PER_PARTICLE.
Merge branch 'master' into rotation_per_particle

Conflicts:
	NEWS
	src/magnetic_non_p3m_methods.c
	src/particle_data.c
	src/rotation.c
Merge branch 'master' into rotation_per_particle
Merge remote branch 'upstream/master'
reverted configure.ac
ghmc thermostat - v1 - still in testing
added ghmc files that were missing from the v1 commit
added experimental temperaure scaling option + some clean up
added ghmc parallelization
Merge branch 'master' of https://github.com/espressomd/espresso into ghmc

* 'master' of https://github.com/espressomd/espresso:
  Fixes to verstion build.
  genversion better posix compatibility
  fixed p3m maximal r_cut for parallel simulations
  Two execs in one sh-file does not make sense.
  Don't force installation of missing files.
  bootstrap.sh forces reconfiguration.
  Version is compiled into documentation.
  small fixes to the GPU LB
  Rearranged analysis chapter.
  UG documentation for FCS autocorrelation function
  git as suffix, not as prefix.
  More version handling.
  Updated version handling.
  Updated NEWS.
  Version handling for dist package.
  Fixed a bug in correlation init
  cmpile git-version into binary.
  First implementation of fcs autocorrelation function.
  Small fixes.
  My first try of git-version.
more efficient energy calculation after momentum update