pelican/utils: Add split_all() and rework static URL generation

I think the conversion from native paths to URLs is best put off until
we are actually trying to generate the URL.  The old handling
(introduced in 2692586, Fixes #645 - Making cross-content linking
windows compatible, 2012-12-19) converted the path at StaticContent
initialization, which left you with a bogus StaticContent.src.

Once we drop the 'static' subdirectory, we will be able to drop the
`dest` and `url` parts from the StaticGenerator.generate_context()
handling, which will leave things looking a good deal cleaner than
they do now.

pelican/generators.py

@@ -25,6 +25,7 @@ from pelican.contents import (
 from pelican.readers import read_file
 from pelican.utils import copy, process_translations, mkdir_p
 from pelican import signals
+import pelican.utils
 
 
 logger = logging.getLogger(__name__)
@@ -518,13 +519,15 @@ class StaticGenerator(Generator):
             for f in self.get_files(
                     os.path.join(self.path, static_path), extensions=False):
                 f_rel = os.path.relpath(f, self.path)
-                # On Windows, make sure we end up with Unix-like paths.
-                if os.name == 'nt':
-                    f_rel = f_rel.replace('\\', '/')
                 # TODO remove this hardcoded 'static' subdirectory
+                dest = os.path.join('static', f_rel)
+                url = '/'.join(pelican.utils.split_all(dest))
                 sc = Static(
                     content=None,
-                    metadata={'save_as': os.path.join('static', f_rel)},
+                    metadata={
+                        'save_as': dest,
+                        'url': url,
+                        },
                     settings=self.settings,
                     source_path=f_rel)
                 self.staticfiles.append(sc)