This commit adds support for the new ipq40xx target.

optional = true does not make sense without a datatype. When no datatype is
set, the empty string will be a valid value, so data is never unset in the
write function. Restore the minlength(1) datatype so the contact setting is
deleted as intended when no value is provided.

The first half was just the package title, the second was outdated.

The field was accidentally removed during the status-page rewrite.

Fixes #1401

gluon-config-mode-contact-info: provide enhancements for german, english and french translation to comply with DSGVO (#1394)

* do not allow to obligatorily require contact information
* add remark that the data is provided voluntarily
* mention how to delete the data
* be very clear about the fact that the data being entered is public and
  can be downloaded and processed by anyone.

This commit adds the ability to show information about the platform on
config-mode reboot.

This commit adds information about:
- how cpu time is spent since boot in jiffies (1/100*sek) (cpu)
    - the value is summed for all cores, so in 10 seconds the
      summed values will increase by 4000, if the cpu has
      4 cores
- context switches since boot (ctxt)
- interrupt counters since boot (intr, softirq)
- forks since boot (processes)

    { "stat": {
       "cpu": {
         "user": 219403,
         "nice": 1714,
         "system": 75159,
         "idle": 2727739,
         "iowait": 2943,
         "irq": 0,
         "softirq": 571
       },
       "intr": 8426340,
       "ctxt": 50992590,
       "processes": 10549,
       "softirq": 5161884
    } }

In multidomain setups, VXLAN is enabled by default, but can be disabled in
domain configs using the mesh/vxlan option. In single domain setups, the
mesh/vxlan option is mandatory.

The UCI option for legacy mode is removed.

Fixes #1364

Fixes: 8e5abf02 ("treewide: switch to ebtables-tiny")

The local_node ifstatus must be checked for local-node, not client. While
we're at it, also clean up the syntax a bit.

batman-adv-specific parts are moved to a new package
gluon-status-page-mesh-batman-adv.

gluon-core, gluon-l3roamd: introduce script gluon-list-mesh-interfaces that lists all currently active mesh interfaces

gluon-status-page: reduce usage of absolute paths in cgi-bin scripts neighbours-nodeinfo and stations

The field is unused.