scheduler mappings system_media rules: adjust cpu.shares
ulatency.match_flag(): include inherited flags if u_proc instance passed
XFCE session manager / panel fix for the whole dekstop being run under one group.
RunnerFix: bad starters don't have to be pgrp leaders

e.g. xfce4-session is not the process group leader.
add xfce4-panel to bad starters
XfceUI: don't inherit user.ui flag
simple.d/xfce.conf: label more xfce4 components
fix o-s-d mappings incorrect reference to user.game label with wrong user.games
fix proc.{vm_swap,vm_exe,vm_lib,rtprio,sched,vsize} exporting tu lua

vm_swap was not pushed to lua table, therefore consequent properties
were shift by one.
improve set_active_pid() in group.c

- Reschedule all affected processes (those with changed list position),
so proc.active_pos works correctly inside lua rules, e.g. when a scheduler
rule checks for proc.acctive_pos == 1 the cgroup will now
contain only the topmost process.

- timestamp of the process last activity can now be passed (updated dbus
/ lua interface accordingly)

- minor optimization (the list is kept sorted, no need for explicit sorting)
ulatency client: add blkio.swappiness and freezer.state to displayed flags
Merge branch 'xfce-fixes'
ulatency tree: fix when requested or default hierarchy is unavailable

- print human readable error if there is no cgroup hierarchy available
- print human readable error if the requested hierarchy is unavailable
- if no hierarchy was specified and the default one (cpu) is
unavailable, select first available

Fixes issue #44