* Add section mark as an extra key in QWERTY-like layouts that don't have it already
* Add dagger (also double dagger) as an extra key in QWERTY-like layouts
`gen_layouts.py` lists the layouts in `res/xml` and generate the
`pref_layout_values` and `pref_layout_entries` arrays into
`res/values/layouts.xml`.
These arrays are hard to maintain as the order has to match, which is
fragile.
This relies on every layouts having a `name` attribute.
