Only update icon quality for wireless

Taken from netspeed commit: be71b6dcc90ee7c2e2431ee79160d837fba7324f
From: Jörgen Scheibengruber <mfcn@gmx.de>
Fix quality calculation and failed assertion

Taken from netspeed commit: 1848ba4107e28c2847b880d01854528197258df8
From: Jörgen Scheibengruber <mfcn@gmx.de>
Disconnect "changed" on icon theme upon destruction

Taken from netspeed commit: dfe9496a0da12f092043e0c90e3b5f6237f678af
From: Jörgen Scheibengruber <mfcn@gmx.de>
Fix out-of-bounds access

Taken from netspeed commit: 225107e053e0a410e43d47daa7f5b0de0d635002
From: Jörgen Scheibengruber <mfcn@gmx.de>
Take maximum quality into account of quality calculation

If this can be queried from the driver.

Taken from netspedd commit: c95746608862d5426dd093c78885ccce6be1c218
From: Jörgen Scheibengruber <mfcn@gmx.de>
Fix compiler warnings

Taken from netspeed commit: d4f00e8e74ca53490cfa9d4265c1c821d3119f8a
From: Jörgen Scheibengruber <mfcn@gmx.de>
Sync translations with transifex