Bugfix: color leak

When switching to a color and back, the stroking color (RG) didn't get reset.
See http://tex.stackexchange.com/questions/133147/ for details
Merge branch 'hotfix_v1.6' into develop_v1.7

* hotfix_v1.6:
  Bugfix: color leak
Merge branch 'develop_v1.7' into develop

* develop_v1.7:
  Bugfix: color leak