Meta: Add icons to online man pages

Previously all the added icons weren't available in the online version
of the man pages. This patch adds functionality to copy all the used
icons over when assembling the HTML version.

Meta/convert-markdown-links.lua

@@ -3,3 +3,14 @@ function Link(el)
     el.target = string.gsub(el.target, "help://man/([^/]*)/(.*)", "../man%1/%2.html")
     return el
 end
+
+function Image(el)
+    local pattern = "/res/icons/(.*)"
+    local image = string.gsub(el.src, pattern, "%1")
+
+    el.src = "../icons/" .. image
+    file = io.open("icons.txt", "a+")
+    file:write(image .. "\n")
+    file:close()
+    return el
+end