announced was renamed to respondd in 2016. Let's remove the obsolete
migration code.

This removes PKG_VERSION and PKG_RELEASE from most Makefiles, as the
value was never useful for Gluon packages; instead, PKG_VERSION is set
to 1 in gluon.mk.

It also removes two other weird definitions:

- gluon-iptables-clamp-mss-to-pmtu replicating the old PKG_VERSION logic
  from gluon-core, but without the fixed PKG_BUILD_DIR to prevent
  unnessary rebuilds
- gluon-hoodselector set GLUON_VERSION=3

Fixes warnings about implicit pointer-to-int and int-to-pointer casts.

Fixes: 59a4cd63 ("gluon-respondd: expose OWE clients in nodeinfo")

This renames the local_client zone to loc_client, as local_clint exceeds
the maximum zone length allowed for firewall3, which is 11 bytes.

This worked previously due to firewall3 using unsafe string operations.
Now creation of the chain fails (latest OpenWrt master).

[Matthias Schiffer: fix up start/stop order and file permissions]

Closes #1974

Situation:
==========

$ ls -l /lib/gluon/domains/lindennord.json
lrwxrwxrwx    1 root     root            10 Jan  6 03:42 /lib/gluon/domains/lindennord.json -> dom17.json

Before:
=======

$ gluon-neighbour-info -d ::1 -p 1001 -r nodeinfo -c 1
{
   "node_id": "525400123456",
   "system": {
     "domain_code": "lindennord",
     "site_code": "ffh"
   },
...
}

After:
======

$ gluon-neighbour-info -d ::1 -p 1001 -r nodeinfo -c 1
{
   "node_id": "525400123456",
   "system": {
     "primary_domain_code": "dom17",
     "domain_code": "lindennord",
     "site_code": "ffh"
   },
...
}

Fixes #1959

Provide the number of OWE stations in addition to the number of all
connected wireless clients.

In addition this PR contains:
- split of gluon-respondd provider into multiple source files
- minor additional cleanups in gluon-mesh-babel respondd provider
  (untested, as the babel respondd provider already doesn't compile prior
  to these changes...)

Fixes #1701

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
    } }

Our provider modules are prefixed with gluon- now, and the log message
about a missing provider dir was confusing users.

[Matthias Schiffer: rebase]

 * gluon-core, gluon-client-bridge: introduce new firewall zone: local_client
 * gluon-core: put clients in local_client zone, introduce drop-zone,
   set dns-rules and zones
 * gluon-respondd: allow respondd on mesh
 * gluon-status-page-api: allow http input on mesh and client

Nothing outside the config mode depends on luci-base anymore.

We also make use of the boolean support of simple-uci to make scripts
clearer.

Rework init script to additionally join a ff05::... multicast group on the mesh-wide interface.

Mesh-wide multicast requests are answered with a random delay of up to 10s.

Because we unconditionally appended `-i br-client` to the command line of
respondd, it wasn't restarted when br-client changed state. Now, we use a
jsonfilter expression on the network.interface dump data, similar to how the
other interface names are generated, and only add the interface to the argument
list if it is up.

Fixes #414

Most doubles that are delivered via respondd have limited input
precision, but are converted with up to 17 digits of precision. That can
cause ugly blowups like 0.2800000000000001 in the output, which is
avoided by specifying better format strings (like "%.2f" in most cases).