v1.52.0 — log-level-unknown, interface-name-too-long

Two new linter smells (62 smells), both error, for lines that stop the file from loading. log-level-unknown: iptables refuses nft's level spellings (warn, err, audit) and nft refuses iptables' (warning, error, numbers) — the finding names the right one. interface-name-too-long: 16 characters is refused by both (15 is the most; the +/* wildcard counts). Measured on iptables 1.8.13 (both backends), ip6tables and nft 1.1.x: iptables-restore stops at the line and INPUT stays at ACCEPT; nft -f refuses the whole ruleset. Two new samples (iptables and its nft mirror), loaded as written. Tests 325. (#73)