rename gateway_nexthop fields in statistics

[christf]

gateway_src and gateway_nexthop are very specific terms and they sit flat in statistics.
There are network topologies that cannot be covered by this structure. Especially when there is src-specific routing in place. Instead of gateway_nexthop I propose the following structure:

gateway: [
{
    "src": "aaa:bbb:ccc:ddd:eee:111:2222:333/64"
    "via": "aaa:bbb:ccc:ddd:eee:111:2222:333/64"
    ("dest": "aaa:bbb:ccc:ddd:eee:111:2222:333/64")
}
]

The terminology "src" and "via" means the structure is re-usable between different mesh protocols.
Optionally we could include a "dest" field as well, however at the moment I guess only 2000::/3 is relevant.

[genofire]

i will implement it, if it is in the master-branch on https://github.com/freifunk-gluon/gluon

[genofire]

is there any update on this, or could we close the yanic issue?