Try to hint reader mode better.

Line breaks in the imageboard parser now use an empty paragraph tag
to try to hint that the page should use reader mode.

assets/style.css

@@ -9,6 +9,7 @@ body{
 }
 h1,h2,h3{line-height:1.2}
 p,.tag-list{margin-bottom:0px}
+.spacer{margin-bottom:1em}
 .spoiler,.spoiler2{background:#444}
 .spoiler:hover,.spoiler2:hover{color:#FFF}
 .greentext{color:#282}

src/lua/parser_imageboard.lua

@@ -99,7 +99,7 @@ local grammar = P{
 	plainline = (V"marked" + word)^0,
 	line = Cs(V"greentext" + V"pinktext" + V"plainline" + P"") * P"\n" / function(a)
 		if a == "\r" then
-			return "<br/>"
+			return [[<p class="spacer"></p>]]
 		else
 			return string.format("<p>%s</p>",a)
 		end