Add "search" option

PLEASE NOTE that this is case sensitive and does really basic research ("is xyz in the title?"). Don't use this for fine filtering.
Also fixed an issue with After(), due to the fact that some functions were removing items from the feed while looping over the feed items, creating some anoying item-skipping issues.

morss/morss.py

@@ -669,7 +669,11 @@ def Gather(rss, url, cache, options):
 
 
 def After(rss, options):
-    for i, item in enumerate(rss.items):
+    for i, item in enumerate(list(rss.items)):
+        if options.search:
+            if options.search not in item.title:
+                item.remove()
+                continue
 
         if item.desc and item.content:
             if options.clip: