Fixed to use best practices for middle of word emphasis

Per https://www.markdownguide.org/basic-syntax#emphasis

mm-go-irckit/userbridge.go

@@ -1187,39 +1187,52 @@ func (u *User) formatCodeBlockText(text string, prefix string, codeBlockBackTick
 // Use static initialisation to optimize.
 // Bold & Italic - https://www.markdownguide.org/basic-syntax#bold-and-italic
 var boldItalicRegExp = []*regexp.Regexp{
-	regexp.MustCompile(`(?:\*\*\*)+?(.+?)(?:\*\*\*)+?`),
-	regexp.MustCompile(`(?:\_\_\_)+?(.+?)(?:\_\_\_)+?`),
-	regexp.MustCompile(`(?:\_\_\*)+?(.+?)(?:\*\_\_)+?`),
-	regexp.MustCompile(`(?:\*\*\_)+?(.+?)(?:\_\*\*)+?`),
+	regexp.MustCompile(`(^|\W)(?:\*\*\*)+?(.+?)(?:\*\*\*)+?(\W|$)`),
+	regexp.MustCompile(`(^|\W)(?:\_\_\_)+?(.+?)(?:\_\_\_)+?(\W|$)`),
+	regexp.MustCompile(`(^|\W)(?:\_\_\*)+?(.+?)(?:\*\_\_)+?(\W|$)`),
+	regexp.MustCompile(`(^|\W)(?:\*\*\_)+?(.+?)(?:\_\*\*)+?(\W|$)`),
 }
 
 // Bold - https://www.markdownguide.org/basic-syntax#bold
 var boldRegExp = []*regexp.Regexp{
-	regexp.MustCompile(`(?:\*\*)+?(.+?)(?:\*\*)+?`),
-	regexp.MustCompile(`(?:\_\_)+?(.+?)(?:\_\_)+?`),
+	regexp.MustCompile(`(^|\W)(?:\*\*)+?(.+?)(?:\*\*)+?(\W|$)`),
+	regexp.MustCompile(`(^|\W)(?:\_\_)+?(.+?)(?:\_\_)+?(\W|$)`),
 }
 
 // Italic - https://www.markdownguide.org/basic-syntax#italic
 var italicRegExp = []*regexp.Regexp{
-	regexp.MustCompile(`(?:\*)+?(.+?)(?:\*)+?`),
-	regexp.MustCompile(`(?:\_)+?(.+?)(?:\_)+?`),
+	regexp.MustCompile(`(^|\W)(?:\*)+?(.+?)(?:\*)+?(\W|$)`),
+	regexp.MustCompile(`(^|\W)(?:\_)+?(.+?)(?:\_)+?(\W|$)`),
 }
 
+// Middle of a word support
+var (
+	subWordBoldItalicRegExp = regexp.MustCompile(`(\w)(?:\*\*\*)+?(.+?)(?:\*\*\*)+?(\w)`)
+	subWordBoldRegExp       = regexp.MustCompile(`(\w)(?:\*\*)+?(.+?)(?:\*\*)+?(\w)`)
+	subWordItalicRegExp     = regexp.MustCompile(`(\w)(?:\*)+?(.+?)(?:\*)+?(\w)`)
+)
+
 func markdown2irc(msg string) string {
 	// Bold & Italic 0x02+0x1d
 	for _, re := range boldItalicRegExp {
-		msg = re.ReplaceAllString(msg, "\x02\x1d$1\x1d\x02")
+		msg = re.ReplaceAllString(msg, "$1\x02\x1d$2\x1d\x02$3")
 	}
+	// Middle of a word
+	msg = subWordBoldItalicRegExp.ReplaceAllString(msg, "$1\x02\x1d$2\x1d\x02$3")
 
 	// Bold 0x02
 	for _, re := range boldRegExp {
-		msg = re.ReplaceAllString(msg, "\x02$1\x02")
+		msg = re.ReplaceAllString(msg, "$1\x02$2\x02$3")
 	}
+	// Middle of a word
+	msg = subWordBoldRegExp.ReplaceAllString(msg, "$1\x02$2\x02$3")
 
 	// Italic 0x1d
 	for _, re := range italicRegExp {
-		msg = re.ReplaceAllString(msg, "\x1d$1\x1d")
+		msg = re.ReplaceAllString(msg, "$1\x1d$2\x1d$3")
 	}
+	// Middle of a word
+	msg = subWordItalicRegExp.ReplaceAllString(msg, "$1\x1d$2\x1d$3")
 
 	return msg
 }