tablet: Copy code from desktop

Update tablet shell code and keep it in synch with desktop.
desktop: Set configuration category

Forgot to set configuration category, without this settings will be
retrieved from the wrong path.
tablet: Set configuration category

Forgot to set configuration category, without this settings will be
retrieved from the wrong path.
client: Use catchsegv to handle crashes

Don't handle shell crashes ourselves and use catchsegv provided by
glibc.
client: Add more debug

On some systems the UI is not load, let's try to understand why with
more debug messages.