V 1.5.1: some code cleanup
V 1.5.1: some code cleanup

# 26.10.2016 V1.5.1   enable/disable MIT-SHM environment variables on HOSTDISPLAY only.
#                     removed variable DOCKERUSER, no longer needed
#                     usage (--help) info correction: use --ipc with --hostuser only, not --hostdisplay 
#                     some code cleanup
#                     only create ADDUSERHOMEFOLDER and symbolic link ~/x11docker if ADDUSERHOMEFOLDER does not exist
mviereck/x11docker