Handle dynamic disk major numbers for dm and mdp virtual devices and don't
add their data to the composite disk.
Disk panel labels configurable - probably mostly useful for user labeling
of virtual disks.
Use wrap bytes instead of discarding data when cumulative chart data overflows.
Pavel Reznicek patch: Theme changes key changed to shift pageup/pagedown.
Ville Skytta patch: indentation cleanup and os_release() bugfix.
493b23da0e