[Feature: 1366] userspace/wrsw_rtud: support setting HP mask

Add to Kconfig:
--RTU_HP_MASK_ENABLE
--RTU_HP_MASK_VAL

Update wrs_vlans:
--add parameter --hpmask
--read RTU_HP_MASK_* from dot-config
--print hpmask with plist

add a new minipc call rtud_export_hp_mask for HP mask

Update wrs-user-manual
Update wrs-developer-manual
Update webinterface

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>