Linux: rename .desktop file to match DBus name

Fixes #785

Add PL translation to CMakeLists.txt

Disable update check for rpi-os release

On rpi-os updates will be handled by apt, so directing the user to the
website is unhelpful.

Merge pull request #728 from tdewey-rpi/release/1.8.3

meta: v1.8.3

Release 1.8.1

Bump version number

Update Italian language

Windows WLAN PSK retrieval: unescape XML

Assuming unescaping standard XML entities is sufficient.
(Skipping numerical unicode XML entities for now, as
there is not a proper standardized way to
represent non-ascii characters in a PSK anyway)

Ref #541

Prevent user from entering invalid characters in hostname field

Implemented as "validator" which will cause that if an user
presses a key that is not allowed, it will not register.
Saves having to add an error message that would need to be
translated to different languages.

Closes #474

Remove overscan/piwiz supression options

- Remove overscan and piwiz supression option
- Change wifi -> wireless LAN
- Bump version