Add vendor files for go build

vendor/github.com/alecthomas/chroma/coalesce.go

@@ -0,0 +1,35 @@
+package chroma
+
+// Coalesce is a Lexer interceptor that collapses runs of common types into a single token.
+func Coalesce(lexer Lexer) Lexer { return &coalescer{lexer} }
+
+type coalescer struct{ Lexer }
+
+func (d *coalescer) Tokenise(options *TokeniseOptions, text string) (Iterator, error) {
+	var prev Token
+	it, err := d.Lexer.Tokenise(options, text)
+	if err != nil {
+		return nil, err
+	}
+	return func() Token {
+		for token := it(); token != (EOF); token = it() {
+			if len(token.Value) == 0 {
+				continue
+			}
+			if prev == EOF {
+				prev = token
+			} else {
+				if prev.Type == token.Type && len(prev.Value) < 8192 {
+					prev.Value += token.Value
+				} else {
+					out := prev
+					prev = token
+					return out
+				}
+			}
+		}
+		out := prev
+		prev = EOF
+		return out
+	}, nil
+}