implement support for multiple pub/mark buttons, add plugin which adds a separate mark button to article botton in combined mode (closes #382)

plugins/mark_button/init.php

@@ -0,0 +1,39 @@
+<?php
+class Mark_Button extends Plugin {
+	private $link;
+	private $host;
+
+	function init($host) {
+		$this->link = $host->get_link();
+		$this->host = $host;
+
+		$host->add_hook($host::HOOK_ARTICLE_BUTTON, $this);
+	}
+
+	function about() {
+		return array(1.0,
+			"Bottom un/star button for the combined mode",
+			"fox");
+	}
+
+	function hook_article_button($line) {
+		$marked_pic = "";
+
+		if (get_pref($this->link, "COMBINED_DISPLAY_MODE")) {
+			if (sql_bool_to_bool($line["marked"])) {
+				$marked_pic = "<img
+					src=\"images/mark_set.svg\"
+					class=\"markedPic\" alt=\"Unstar article\"
+					onclick='toggleMark($id)'>";
+			} else {
+				$marked_pic = "<img
+					src=\"images/mark_unset.svg\"
+					class=\"markedPic\" alt=\"Star article\"
+					onclick='toggleMark($id)'>";
+			}
+		}
+
+		return $marked_pic;
+	}
+}
+?>