Updated documentation

* Added paragraph and example about returning tuples from a filter
  (Issue #859)

* Added section about manualpois
  (Issue #858, Issue #869, Issue #598)

* Fixed a typo in the FAQ

* Added logging to file to the FAQ
  (Issue #871)

docs/signs.rst

@@ -47,6 +47,13 @@ A more complicated filter function can construct a more customized display text:
         if poi['id'] == "Chest":
             return "Chest with %d items" % len(poi['Items'])
 
+It is also possible to return a tuple from the filter function to specify a hovertext
+different from the text displayed in the info window. The first entry of the tuple will
+be used as the hover text, the second will be used as the info window content::
+
+    def chestFilter(poi):
+        if poi['id'] == "Chest":
+            return ("Chest", "Chest with %d items" % len(poi['Items']))
 
 Since writing these filters can be a little tedious, a set of predefined filters
 functions are provided.  See the :ref:`predefined_filter_functions` section for
@@ -81,6 +88,67 @@ Here's an example that displays icons for each player::
 
 Note how each POI can get a different icon by setting ``poi['icon']``
 
+Manual POIs
+-----------
+
+It is also possible to manually define markers. Each render can have a render dictionary key
+called ``manualpois``, which is a list of dicts. Each dict represents a marker, and is required
+to have at least the attributes ``x``, ``y``, ``z`` and ``id``, with the coordinates being Minecraft
+world coordinates. (i.e. what you see in-game when you press F3)
+
+An example which adds two POIs with the id "town", and then uses a filter function to filter for them::
+
+    def townFilter(poi):
+        if poi['id'] == 'Town':
+            return poi['name']
+
+            
+    renders['myrender'] = {
+        'world':'myworld',
+        'title':'Example',
+        'manualpois':[
+                       {'id':'Town',
+                        'x':200,
+                        'y':64,
+                        'z':200,
+                        'name':'Foo'},
+                       {'id':'Town',
+                        'x':-300,
+                        'y':85,
+                        'z':-234,
+                        'name':'Bar'}],
+        'markers': [dict(name="Towns", filterFunction=townFilter, icon="town.png")],
+    }
+
+Here is a more complex example where not every marker of a certain id has a certain key::
+
+    def townFilter(poi):
+        if poi['id'] == 'Town':
+            try:
+                return (poi['name'], poi['description'])
+            except KeyError:
+                return poi['name'] + '\n'
+
+            
+    renders['myrender'] = {
+        'world':'myworld',
+        'title':'Example',
+        'manualpois':[
+                       {'id':'Town',
+                        'x':200,
+                        'y':64,
+                        'z':200,
+                        'name':'Foo',
+                        'description':'Best place to eat hamburgers'},
+                       {'id':'Town',
+                        'x':-300,
+                        'y':85,
+                        'z':-234,
+                        'name':'Bar'}],
+        'markers': [dict(name="Towns", filterFunction=townFilter, icon="town.png")],
+    }
+    
+
 Render Dictionary Key
 ---------------------