Add support for markdown to HTML conversion (matrix). Closes #663 (#670)

This uses our own gomatrix lib with the SendHTML function which
adds HTML to formatted_body in matrix.
golang-commonmark is used to convert markdown into valid HTML.

vendor/gitlab.com/golang-commonmark/markdown/urlschema.go

@@ -0,0 +1,185 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package markdown
+
+var urlSchemas = []string{
+	"aaa",
+	"aaas",
+	"about",
+	"acap",
+	"adiumxtra",
+	"afp",
+	"afs",
+	"aim",
+	"apt",
+	"attachment",
+	"aw",
+	"beshare",
+	"bitcoin",
+	"bolo",
+	"callto",
+	"cap",
+	"chrome",
+	"chrome-extension",
+	"cid",
+	"coap",
+	"com-eventbrite-attendee",
+	"content",
+	"crid",
+	"cvs",
+	"data",
+	"dav",
+	"dict",
+	"dlna-playcontainer",
+	"dlna-playsingle",
+	"dns",
+	"doi",
+	"dtn",
+	"dvb",
+	"ed2k",
+	"facetime",
+	"feed",
+	"file",
+	"finger",
+	"fish",
+	"ftp",
+	"geo",
+	"gg",
+	"git",
+	"gizmoproject",
+	"go",
+	"gopher",
+	"gtalk",
+	"h323",
+	"hcp",
+	"http",
+	"https",
+	"iax",
+	"icap",
+	"icon",
+	"im",
+	"imap",
+	"info",
+	"ipn",
+	"ipp",
+	"irc",
+	"irc6",
+	"ircs",
+	"iris",
+	"iris.beep",
+	"iris.lwz",
+	"iris.xpc",
+	"iris.xpcs",
+	"itms",
+	"jar",
+	"javascript",
+	"jms",
+	"keyparc",
+	"lastfm",
+	"ldap",
+	"ldaps",
+	"magnet",
+	"mailto",
+	"maps",
+	"market",
+	"message",
+	"mid",
+	"mms",
+	"ms-help",
+	"msnim",
+	"msrp",
+	"msrps",
+	"mtqp",
+	"mumble",
+	"mupdate",
+	"mvn",
+	"news",
+	"nfs",
+	"ni",
+	"nih",
+	"nntp",
+	"notes",
+	"oid",
+	"opaquelocktoken",
+	"palm",
+	"paparazzi",
+	"platform",
+	"pop",
+	"pres",
+	"proxy",
+	"psyc",
+	"query",
+	"res",
+	"resource",
+	"rmi",
+	"rsync",
+	"rtmp",
+	"rtsp",
+	"secondlife",
+	"service",
+	"session",
+	"sftp",
+	"sgn",
+	"shttp",
+	"sieve",
+	"sip",
+	"sips",
+	"skype",
+	"smb",
+	"sms",
+	"snmp",
+	"soap.beep",
+	"soap.beeps",
+	"soldat",
+	"spotify",
+	"ssh",
+	"steam",
+	"svn",
+	"tag",
+	"teamspeak",
+	"tel",
+	"telnet",
+	"tftp",
+	"things",
+	"thismessage",
+	"tip",
+	"tn3270",
+	"tv",
+	"udp",
+	"unreal",
+	"urn",
+	"ut2004",
+	"vemmi",
+	"ventrilo",
+	"view-source",
+	"webcal",
+	"ws",
+	"wss",
+	"wtai",
+	"wyciwyg",
+	"xcon",
+	"xcon-userid",
+	"xfire",
+	"xmlrpc.beep",
+	"xmlrpc.beeps",
+	"xmpp",
+	"xri",
+	"ymsgr",
+	"z39.50r",
+	"z39.50s",
+}
+
+var urlSchemasSet = make(map[string]bool)
+
+func init() {
+	for _, s := range urlSchemas {
+		urlSchemasSet[s] = true
+	}
+}
+
+func matchSchema(s string) bool {
+	_, ok := urlSchemasSet[s]
+	return ok
+}