p1: /v2/scrape, /v1/fetch, auth, CLI, contract tests

Single Fetcher.Fetch on the Guard that holds DenyPrefixes. skipTlsVerification
is ignored. No 502. keys add writes the secret only to --out. Release binary
has no -test-allow-prefix.

vendor/github.com/go-shiori/go-readability/Makefile

@@ -0,0 +1,10 @@
+generate:
+	@for name in internal/re2go/*.re; do \
+		RE_IN=$$name; \
+		RE_OUT=$$(echo $$name | sed 's/\.re/.go/'); \
+		re2go -W -F --input-encoding utf8 --utf8 --no-generation-date -i $$RE_IN -o $$RE_OUT; \
+		gofmt -w $$RE_OUT; \
+	done
+
+test: generate
+	go test -timeout 30s ./...