Issue templates directory (#11450)

* Issue templates

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add some comments, appease the linter

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add docs and re-use dir candidates

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add default labels to issue templates

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Generate swagger

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Suggested changes

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Update issue.go

* Suggestions

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Extract metadata from legacy if possible

Signed-off-by: jolheiser <john.olheiser@gmail.com>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/markup/markdown/meta.go

@@ -0,0 +1,49 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package markdown
+
+import (
+	"errors"
+	"strings"
+
+	"gopkg.in/yaml.v2"
+)
+
+func isYAMLSeparator(line string) bool {
+	line = strings.TrimSpace(line)
+	for i := 0; i < len(line); i++ {
+		if line[i] != '-' {
+			return false
+		}
+	}
+	return len(line) > 2
+}
+
+// ExtractMetadata consumes a markdown file, parses YAML frontmatter,
+// and returns the frontmatter metadata separated from the markdown content
+func ExtractMetadata(contents string, out interface{}) (string, error) {
+	var front, body []string
+	var seps int
+	lines := strings.Split(contents, "\n")
+	for idx, line := range lines {
+		if seps == 2 {
+			front, body = lines[:idx], lines[idx:]
+			break
+		}
+		if isYAMLSeparator(line) {
+			seps++
+			continue
+		}
+	}
+
+	if len(front) == 0 && len(body) == 0 {
+		return "", errors.New("could not determine metadata")
+	}
+
+	if err := yaml.Unmarshal([]byte(strings.Join(front, "\n")), out); err != nil {
+		return "", err
+	}
+	return strings.Join(body, "\n"), nil
+}