Unblank display when shutting down/rebooting from act dead or user mode

Previously display was blanked when shutting down from act dead. As there
is now shutdown animation also for act dead, that is no longer desirable.

Unblanking the display makes the animation visible even if the shutdown
or reboot happened from display off state without user interaction.
Keep frame buffer device opened to keep display from powering off

When mce starts up, it will keep the fbdev open until actdead or
user mode is reached. This should keep the display powered on and
not lose content during bootup.

When shutdown is initiated (and not canceled), mce opens fbdev and
keeps it open for a while even after mce exits to allow shutdown
animation to stay visible.

[mce] Keep frame buffer device opened to keep display from powering off. Fixes JB#14341
Adjust display linger times after ending a call

When call ends the linger time specifies the length of time during
which the display will turn on / stay on if proximity is uncovered
before previous display state and normal blanking policy is restored.

For incoming calls the linger time should be long enough to allow the
user to select "call again" or similar continuation actions. For now
5 seconds is used.

For outgoing calls the linger time should be long enough to allow the
user to remove the device from ear. For now 2.5 seconds is used.

[mce] Adjust display linger times after ending a call. Fixes JB#20810
Blanking inhibit mode is evaluated also during call

If automatic blanking is disabled, it should stay disabled also
during active call.
Do not turn display on after linger time if proximity sensor is covered

Also, unless the display was clearly on when the the exceptional
situation started, the display is turned off after linger time.
Merge pull request #185 from spiiroin/delay_shutdown_blanking

Delay display blanking during shutdown
Merge pull request #186 from spiiroin/end_of_call_linger

End of call display linger
Bump mce version to 1.32.1