Don't rewrite URLs

Remove the code that was appending ../static in front of some URLs, and add a
way to do cross-content linking.

pelican/__init__.py

@@ -134,6 +134,7 @@ class Pelican(object):
         """Run the generators and return"""
 
         context = self.settings.copy()
+        filenames = {}  # share the dict between all the generators
         generators = [
             cls(
                 context,
@@ -142,7 +143,8 @@ class Pelican(object):
                 self.theme,
                 self.output_path,
                 self.markup,
-                self.delete_outputdir
+                self.delete_outputdir,
+                filenames=filenames
             ) for cls in self.get_generator_classes()
         ]