Petitboot v1.6.0 and v1.5.2 tagged

[Samuel Mendoza-Jonas]

Petitboot v1.6.0 has been tagged, including several small fixes and an update
to support pb-plugins in the Petitboot UI.

- Reduce noise from calling LVM utilities
LVM utilities such as vgscan warn on any open file descriptors when called.
Aside from one fix these are required for process IO, so these warnings are
suppressed.

- Update struct field size for current libflash

- Properly clear safe mode warning on reinit, and preserve configuration
correctly when clearing a safe mode IPMI override.

- Translation update for all languages.

- Add new UI support for finding, installing, and running Petitboot Plugins.
This adds a new Plugins menu interface for discovered pb-plugins. These are
discovered automatically on mounted storage devices, or by using the "PLUGIN"
label in PXE configs. Each plugin can be installed via the Plugin menu, and
then investigated and run from a per-plugin interface.


Petitboot v1.5.2 has also been tagged which includes the above fixes without the
major Plugin update. This is intended for current users who are building a
new stable platform with Petitboot. v1.5.x releases will continue to be tagged
to provide future fixes, and replaces the v1.2.x releases.