Added `livehtml` doc loader, and updated docs on `MethodFilter`

docs/Makefile

@@ -151,3 +151,5 @@ doctest:
 	$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
 	@echo "Testing of doctests in the sources finished, look at the " \
 	      "results in $(BUILDDIR)/doctest/output.txt."
+livehtml:
+	sphinx-autobuild -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html

docs/usage.txt

@@ -115,6 +115,72 @@ default filters for all the models fields of the same kind using
             fields = ['name']
 
 
+MethodFilter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+If you want fine control over each individual filter attribute, you can use
+the ``MethodFilter`` filter.
+
+By passing in the name of a custom defined filter function as an ``action``,
+the filter attribute gets linked to the custom filter function.
+Here is an example of overriding the filter function of the
+filter attribute ``username``
+::
+
+    class F(django_filters.FilterSet):
+            username = MethodFilter(action='my_custom_filter')
+
+            class Meta:
+                model = User
+                fields = ['username']
+
+            def my_custom_filter(self, queryset, value):
+                return queryset.filter(
+                    username=value
+                )
+
+
+The filter function can also be defined outside of the filter class scope.
+Though you would need to pass in the actual function value, not it's name.
+::
+
+        def my_custom_filter(queryset, value):
+            return queryset.filter(
+                username=value
+            )
+
+        class F(django_filters.FilterSet):
+	    # Notice: In this case, action accepts a func, not a string
+            username = MethodFilter(action=filter_username)
+
+            class Meta:
+                model = User
+                fields = ['username']
+
+
+Lastly, when using a ``MethodFilter``, there is no need to define an action.
+You may simply do the following and ``filter_username`` will be auto-detected
+and used. ::
+
+        class F(FilterSet):
+            username = MethodFilter()
+
+            class Meta:
+                model = User
+                fields = ['username']
+
+            def filter_username(self, queryset, value):
+                return queryset.filter(
+                    username__contains='ke'
+                )
+
+Under the hood, if ``action`` not is defined, ``django_filter``
+searches for a class method with a name that follows the pattern
+``filter_{{ATTRIBUTE_NAME}}``. For example, if the attribute name is
+``email``, then the filter class will be scanned for the filter function
+``filter_email``. If no action is provided, and no filter class
+function is found, then the filter attribute will be left unfiltered.
+
+
 The view
 --------
 

requirements/test.txt

@@ -2,3 +2,4 @@ Django
 django-discover-runner
 mock
 coverage
+sphinx-autobuild