Update markdown parsing library to github.com/gomarkdown/markdown (#944)

vendor/github.com/gomarkdown/markdown/parser/options.go

@@ -0,0 +1,32 @@
+package parser
+
+import (
+	"github.com/gomarkdown/markdown/ast"
+)
+
+// Flags control optional behavior of parser.
+type Flags int
+
+// Options is a collection of supplementary parameters tweaking the behavior of various parts of the parser.
+type Options struct {
+	ParserHook    BlockFunc
+	ReadIncludeFn ReadIncludeFunc
+
+	Flags Flags // Flags allow customizing parser's behavior
+}
+
+// Parser renderer configuration options.
+const (
+	FlagsNone        Flags = 0
+	SkipFootnoteList Flags = 1 << iota // Skip adding the footnote list (regardless if they are parsed)
+)
+
+// BlockFunc allows to registration of a parser function. If successful it
+// returns an ast.Node, a buffer that should be parsed as a block and the the number of bytes consumed.
+type BlockFunc func(data []byte) (ast.Node, []byte, int)
+
+// ReadIncludeFunc should read the file under path and returns the read bytes,
+// from will be set to the name of the current file being parsed. Initially
+// this will be empty. address is the optional address specifier of which lines
+// of the file to return. If this function is not set no data will be read.
+type ReadIncludeFunc func(from, path string, address []byte) []byte