vtf charges-workaround, prepare_vmd connection moved to vtf

Conflicts:
	scripts/auxiliary.tcl
Updated NEWS.
Updated copyright headers and added GPL header to files where it was missing.
Merge branch '3.1'

Conflicts:
	doc/ug/io.tex
	samples/check_potential.tcl
	samples/diamond.tcl
	samples/lj_benchmark.tcl
	samples/maggs.tcl
	scripts/auxiliary.tcl
	tools/series.tcl
	tools/watch.tcl
Added forgotten copyright header and license.
Repaired header inclusion.
Merge branch 'master' of github.com:espressomd/espresso