whonixcheck, timesync: implemented separate "Lock file /var/run/whonix/package_manager_lock exists. Waiting for it to be removed..." message.
debugging
No longer installing a kernel when --bare-metal switch is used:
Bare metal users have already a working kernel, otherwise the build
script could not have reached this point. Installing a kernel for bare
metal users is not necessary. Installing an extra kernel could even
trigger a bug in grub and make the systen unbootable or install a pae
kernel for users who either do not a system supporting pae or who do not
have pae.
Installing a kernel is only necessary for virtual machine builds,
because virtual machine images are created while their kernel is neither
running nor installed at this point.