Sorting things alphabetically does not do a two level sort

[spacemanspiff2007]

Maybe related to #792

The problem

Sorting things alphabetically only considers the first character. Things are not sorted alphabetically inside the character view. e.g.

Shelly
Squeezebox
Shelly

Expected behavior

When grouped by first character things should be fully sorted alphabetically, e.g.

Shelly
Shelly
Squeezebox

Steps to reproduce

Have different things with the same first character

Your environment

runtimeInfo:
  version: 3.3.0
  buildString: Release Build
locale: de-DE