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/JohannesKaufmann/html-to-markdown/v2/collapse/is_node.go

@@ -0,0 +1,43 @@
+package collapse
+
+import (
+	"github.com/JohannesKaufmann/dom"
+	"golang.org/x/net/html"
+)
+
+var blockElements = []string{
+	"address", "article", "aside", "audio", "blockquote", "body", "canvas", "center", "dd", "dir", "div", "dl", "dt", "fieldset", "figcaption", "figure", "footer", "form", "frameset", "h1", "h2", "h3", "h4", "h5", "h6", "header", "hgroup", "hr", "html", "isindex", "li", "main", "menu", "nav", "noframes", "noscript", "ol", "output", "p", "pre", "section", "table", "tbody", "td", "tfoot", "th", "thead", "tr", "ul",
+}
+
+var voidElements = []string{
+	// Note: Compared to the javascript implementation, I removed "source"
+	"area", "base", "br", "col", "command", "embed", "hr", "img", "input", "keygen", "link", "meta", "param" /* "source, "*/, "track", "wbr",
+}
+
+var defaultIsBlockNode = func(node *html.Node) bool {
+	name := dom.NodeName(node)
+
+	for _, elem := range blockElements {
+		if elem == name {
+			return true
+		}
+	}
+	return false
+}
+var defaultIsVoidNode = func(node *html.Node) bool {
+	name := dom.NodeName(node)
+
+	for _, elem := range voidElements {
+		if elem == name {
+			return true
+		}
+	}
+	return false
+}
+var defaultIsPreformattedNode = func(node *html.Node) bool {
+	// Note: Originally in the javascript version, this just checked for "pre".
+	// I changed it, to also return true for "code"
+	name := dom.NodeName(node)
+
+	return name == "pre" || name == "code"
+}