fix runechat being jank with emphasis (#799)

code/game/say.dm

@@ -141,7 +141,7 @@ GLOBAL_LIST_INIT(freqtospan, list(
 /// Transforms the speech emphasis mods from [/atom/movable/proc/say_emphasis] into the appropriate HTML tags. Includes escaping.
 #define ENCODE_HTML_EMPHASIS(input, char, html, varname) \
 	var/static/regex/##varname = regex("(?<!\\\\)[char](.+?)(?<!\\\\)[char]", "g");\
-	input = varname.Replace_char(input, "<[html]>$1</[html]>")
+	input = varname.Replace_char(input, "<[html]>$1</[html]>&#8203;") //zero-width space to force maptext to respect closing tags.
 
 /// Scans the input sentence for speech emphasis modifiers, notably |italics|, +bold+, and _underline_ -mothblocks
 /atom/movable/proc/say_emphasis(input)