WIP: Fixed support for freeze/standby/suspend/hybrid suspend/hibernate #2

Suggest to compile TDE/tdebase#16 after this.

Based on info from here:

https://www.kernel.org/doc/Documentation/power/states.txt

https://www.kernel.org/doc/Documentation/power/interface.txt

It looks like /sys/power/mem_sleep is new from kernel >= 4.14. We need functionality even for older versions of kernels. The code needs to be changed.

yes, as I mentioned yesterday on the chat, I need to fix support for when mem_sleep is not available. I will work on this during the weekend.

In the current PR, it only affects "Suspend".

PR should now be able to support both older and newer kernel.

I have tested this (together with TDE/tdebase#16) under Slackware in a VirtualBox machines.

The options displayed on the shutdown dialog are consistent with the content of /sys/power/state and /sys/power/disk and their functionality works fine.

I could test freeze, hibernate and hybrid hibernate. The last two behaves the same in this system, since there is no support for suspend-to-RAM but /sys/power/disk contains "suspend"

Rebased to latest master. IMO, this PR is ready for merging.

as per discussion on jabber, more work is required to allow user hibernation

This is hopefully the final one 😄

Tested as simple user and as root, all available actions are possible. Actions tested are freeze, suspend, hydrid suspend and hibernate

new version with polkit support

I have added DBus standard interface Introspect, Peer and Properties to the tde hw daemon. This should solve issue #9 and #12.

I see two potential side effect, but need further testing to make sure they are related to this PR. Further testing is needed before merge. Core functionality is there though.