apps: rename 'search' to 'duckduckgo'

just in case we want to bring in a 'real' search app like e.g.
the one in wercchan, for which see
https://github.com/kfarwell/werchan/tree/master/apps/search

apps/duckduckgo/app.rc

@@ -0,0 +1,29 @@
+fn conf_enable_duckduckgo {
+    enable_duckduckgo=yes
+    conf_enable_app duckduckgo
+		pageTitle='Site Search'
+}
+
+
+fn duckduckgo_init {
+	get_post_args q
+	if (! ~ $#q 0) {
+		redirect_string = 'https://duckduckgo.com/?q=site:'$SERVER_NAME^'+'^$"q
+		http_redirect $redirect_string '302 Found'
+	}
+	if not {
+		handler_body_main='duckduckgo_body'
+	}
+}
+
+fn duckduckgo_body {
+    echo '
+<h1>Site search</h1>
+<h3>using DuckDuckGo</h3>
+<form action="/_search/" method="POST">
+<input type="text" name="q" placeholder="Search text...">
+<input type="submit" value="Search">
+</form>'
+
+}
+