Add StripMarkdown option (irc). (#1145)

Enable `StripMarkdown` to strip markdown for irc.

vendor/github.com/writeas/go-strip-markdown/.gitignore

@@ -0,0 +1,3 @@
+*~
+*.swp
+cmd/strip/strip

vendor/github.com/writeas/go-strip-markdown/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Write.as
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/writeas/go-strip-markdown/README.md

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+# go-strip-markdown
+
+[![GoDoc](https://godoc.org/github.com/writeas/go-strip-markdown?status.svg)](https://godoc.org/github.com/writeas/go-strip-markdown)
+
+A Markdown stripper written in Go (golang).
+
+## Usage
+You could create a simple command-line utility:
+
+```go
+package main
+
+import (
+	"fmt"
+	"github.com/writeas/go-strip-markdown"
+	"os"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		os.Exit(1)
+	}
+	fmt.Println(stripmd.Strip(os.Args[1]))
+}
+```
+
+You could pass it Markdown and get pure, beauteous text in return:
+
+```bash
+./strip "# A Tale of Text Formatting
+
+_One fateful day_ a developer was presented with [Markdown](https://daringfireball.net/projects/markdown/).
+And they wanted **none of it**."
+
+# A Tale of Text Formatting
+#
+# One fateful day a developer was presented with Markdown.
+# And they wanted none of it.
+```
+
+## Inspiration
+This was largely based off of [remove-markdown](https://github.com/stiang/remove-markdown), a Markdown stripper written in Javascript.
+
+## Used by
+
+This library is used in these projects:
+
+* [WriteFreely](https://github.com/writeas/writefreely)
+
+## License
+MIT.

vendor/github.com/writeas/go-strip-markdown/strip.go

@@ -0,0 +1,66 @@
+// Package stripmd strips Markdown from text
+package stripmd
+
+import (
+	"regexp"
+)
+
+var (
+	listLeadersReg = regexp.MustCompile(`(?m)^([\s\t]*)([\*\-\+]|\d\.)\s+`)
+
+	headerReg = regexp.MustCompile(`\n={2,}`)
+	strikeReg = regexp.MustCompile(`~~`)
+	codeReg   = regexp.MustCompile("`{3}" + `.*\n`)
+
+	htmlReg         = regexp.MustCompile("<(.*?)>")
+	emphReg         = regexp.MustCompile(`\*\*([^*]+)\*\*`)
+	emphReg2        = regexp.MustCompile(`\*([^*]+)\*`)
+	emphReg3        = regexp.MustCompile(`__([^_]+)__`)
+	emphReg4        = regexp.MustCompile(`_([^_]+)_`)
+	setextHeaderReg = regexp.MustCompile(`^[=\-]{2,}\s*$`)
+	footnotesReg    = regexp.MustCompile(`\[\^.+?\](\: .*?$)?`)
+	footnotes2Reg   = regexp.MustCompile(`\s{0,2}\[.*?\]: .*?$`)
+	imagesReg       = regexp.MustCompile(`\!\[(.*?)\]\s?[\[\(].*?[\]\)]`)
+	linksReg        = regexp.MustCompile(`\[(.*?)\][\[\(].*?[\]\)]`)
+	blockquoteReg   = regexp.MustCompile(`>\s*`)
+	refLinkReg      = regexp.MustCompile(`^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$`)
+	atxHeaderReg    = regexp.MustCompile(`(?m)^\#{1,6}\s*([^#]+)\s*(\#{1,6})?$`)
+	atxHeaderReg2   = regexp.MustCompile(`([\*_]{1,3})(\S.*?\S)?P1`)
+	atxHeaderReg3   = regexp.MustCompile("(?m)(`{3,})" + `(.*?)?P1`)
+	atxHeaderReg4   = regexp.MustCompile(`^-{3,}\s*$`)
+	atxHeaderReg5   = regexp.MustCompile("`(.+?)`")
+	atxHeaderReg6   = regexp.MustCompile(`\n{2,}`)
+)
+
+// Strip returns the given string sans any Markdown.
+// Where necessary, elements are replaced with their best textual forms, so
+// for example, hyperlinks are stripped of their URL and become only the link
+// text, and images lose their URL and become only the alt text.
+func Strip(s string) string {
+	res := s
+	res = listLeadersReg.ReplaceAllString(res, "$1")
+
+	res = headerReg.ReplaceAllString(res, "\n")
+	res = strikeReg.ReplaceAllString(res, "")
+	res = codeReg.ReplaceAllString(res, "")
+
+	res = emphReg.ReplaceAllString(res, "$1")
+	res = emphReg2.ReplaceAllString(res, "$1")
+	res = emphReg3.ReplaceAllString(res, "$1")
+	res = emphReg4.ReplaceAllString(res, "$1")
+	res = htmlReg.ReplaceAllString(res, "$1")
+	res = setextHeaderReg.ReplaceAllString(res, "")
+	res = footnotesReg.ReplaceAllString(res, "")
+	res = footnotes2Reg.ReplaceAllString(res, "")
+	res = imagesReg.ReplaceAllString(res, "$1")
+	res = linksReg.ReplaceAllString(res, "$1")
+	res = blockquoteReg.ReplaceAllString(res, "  ")
+	res = refLinkReg.ReplaceAllString(res, "")
+	res = atxHeaderReg.ReplaceAllString(res, "$1")
+	res = atxHeaderReg2.ReplaceAllString(res, "$2")
+	res = atxHeaderReg3.ReplaceAllString(res, "$2")
+	res = atxHeaderReg4.ReplaceAllString(res, "")
+	res = atxHeaderReg5.ReplaceAllString(res, "$1")
+	res = atxHeaderReg6.ReplaceAllString(res, "\n\n")
+	return res
+}

vendor/modules.txt

@@ -200,6 +200,8 @@ github.com/technoweenie/multipartstreamer
 github.com/valyala/bytebufferpool
 # github.com/valyala/fasttemplate v1.1.0
 github.com/valyala/fasttemplate
+# github.com/writeas/go-strip-markdown v2.0.1+incompatible
+github.com/writeas/go-strip-markdown
 # github.com/yaegashi/msgraph.go v0.1.2
 github.com/yaegashi/msgraph.go/beta
 github.com/yaegashi/msgraph.go/jsonx