When adding device classes, targets without devices such as x86 were not
handled. As site and feature packages are included on such a per-device
decision, x86 images ended up without most packages.

Include a class setting for a target and include the class-packages
target-wide when this setting is configured.

Fixes 9c523650 ("build: introduce device classes")

It seems the CT variant was used for 11s meshing on x86 by accient. Switch
to non-CT to match the other targets.

The old bash-based parsing code was way too complex. Replace it with Lua.

Let's keep the default package selection to hardware support.

Fixes #1022

As the Gluon kernel won't be compatible with the OpenWrt upstream anymore,
we don't need the vermagic hack anymore.

This also takes us past the OpenWrt 15.05 final release.

The file targets/$GLUON_TARGET/config becomes optional, as many targets
only used it to set the board and subtarget.

Also fix targets without subtarget.