Fix regression in HTML handling (telegram). Closes #734

* Revert back to blackfriday v1
* Add testing

bridge/telegram/html.go

@@ -3,7 +3,6 @@ package btelegram
 import (
 	"bytes"
 	"html"
-	"io"
 
 	"github.com/russross/blackfriday"
 )
@@ -33,7 +32,7 @@ func (options *customHTML) Header(out *bytes.Buffer, text func() bool, level int
 	options.Paragraph(out, text)
 }
 
-func (options *customHTML) HRule(out io.ByteWriter) {
+func (options *customHTML) HRule(out *bytes.Buffer) {
 	out.WriteByte('\n') //nolint:errcheck
 }
 
@@ -54,16 +53,13 @@ func (options *customHTML) ListItem(out *bytes.Buffer, text []byte, flags int) {
 }
 
 func makeHTML(input string) string {
-	extensions := blackfriday.NoIntraEmphasis |
-		blackfriday.FencedCode |
-		blackfriday.Autolink |
-		blackfriday.SpaceHeadings |
-		blackfriday.HeadingIDs |
-		blackfriday.BackslashLineBreak |
-		blackfriday.DefinitionLists
-
-	renderer := &customHTML{blackfriday.NewHTMLRenderer(blackfriday.HTMLRendererParameters{
-		Flags: blackfriday.UseXHTML | blackfriday.SkipImages,
-	})}
-	return string(blackfriday.Run([]byte(input), blackfriday.WithExtensions(extensions), blackfriday.WithRenderer(renderer)))
+	return string(blackfriday.Markdown([]byte(input),
+		&customHTML{blackfriday.HtmlRenderer(blackfriday.HTML_USE_XHTML|blackfriday.HTML_SKIP_IMAGES, "", "")},
+		blackfriday.EXTENSION_NO_INTRA_EMPHASIS|
+			blackfriday.EXTENSION_FENCED_CODE|
+			blackfriday.EXTENSION_AUTOLINK|
+			blackfriday.EXTENSION_SPACE_HEADERS|
+			blackfriday.EXTENSION_HEADER_IDS|
+			blackfriday.EXTENSION_BACKSLASH_LINE_BREAK|
+			blackfriday.EXTENSION_DEFINITION_LISTS))
 }